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Spectral Properties of Dual Unit Gain Graphs 双单元增益图的频谱特性
Pub Date : 2024-09-03 DOI: 10.3390/sym16091142
Chunfeng Cui, Yong Lu, Liqun Qi, Ligong Wang
In this paper, we study dual quaternion, dual complex unit gain graphs, and their spectral properties in a unified frame of dual unit gain graphs. Unit dual quaternions represent rigid movements in the 3D space, and have wide applications in robotics and computer graphics. Dual complex numbers have found application in brain science recently. We establish the interlacing theorem for dual unit gain graphs, and show that the spectral radius of a dual unit gain graph is always not greater than the spectral radius of the underlying graph, and these two radii are equal if, and only if, the dual gain graph is balanced. By using dual cosine functions, we establish the closed form of the eigenvalues of adjacency and Laplacian matrices of dual complex and quaternion unit gain cycles. We then show the coefficient theorem holds for dual unit gain graphs. Similar results hold for the spectral radius of the Laplacian matrix of the dual unit gain graph too.
本文在双单位增益图的统一框架下研究了双四元数、双复数单位增益图及其谱特性。单位双四元数表示三维空间中的刚性运动,在机器人和计算机图形学中有着广泛的应用。最近,双复数在脑科学中得到了应用。我们建立了双单位增益图的交错定理,并证明了双单位增益图的谱半径总是不大于底层图的谱半径,而且当且仅当双增益图平衡时,这两个半径相等。通过使用对偶余弦函数,我们建立了对偶复数和四元单位增益循环的邻接矩阵和拉普拉斯矩阵特征值的封闭形式。然后,我们证明系数定理适用于对偶单位增益图。类似的结果也适用于对偶单位增益图的拉普拉斯矩阵谱半径。
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引用次数: 0
The Impact of the Nonlinear Integral Positive Position Feedback (NIPPF) Controller on the Forced and Self-Excited Nonlinear Beam Flutter Phenomenon 非线性积分正位置反馈 (NIPPF) 控制器对强制和自激非线性梁扑现象的影响
Pub Date : 2024-09-03 DOI: 10.3390/sym16091143
Khalid Alluhydan, Yasser A. Amer, Ashraf Taha EL-Sayed, Marwa Abdelaziz EL-Sayed
This article presents a novel approach to impact regulation of nonlinear vibrational responses in a beam flutter system subjected to harmonic excitation. This study introduces the use of a Nonlinear Integral Positive Position Feedback (NIPPF) controller for this purpose. This technique models the system as a three-degree-of-freedom nonlinear system representing the beam flutter, coupled with a first-order and a second-order filter representing the NIPPF controller. By applying perturbation analysis to the linearized system model, the authors obtain analytical solutions for the autonomous system with the controller. This study aims to reduce vibration amplitudes in a nonlinear dynamic system, specifically when 1:1 internal resonance occurs. The Routh–Hurwitz criterion is utilized to evaluate the system’s stability. Furthermore, the frequency–response curves (FRCs) exhibit symmetry across a range of parameter values. The findings highlight that the effectiveness of vibration suppression is directly related to the product of the NIPPF control signal after comparing with different controllers. Numerical simulations, conducted using the fourth-order Runge–Kutta method, validate the analytical solutions and demonstrate the system’s amplitude response. The strong correlation between the analytical and numerical results highlights the accuracy and dependability of the proposed method.
本文介绍了一种新方法,用于对受到谐波激励的梁扑动系统中的非线性振动响应进行冲击调节。研究介绍了非线性积分正位置反馈 (NIPPF) 控制器的使用方法。该技术将系统建模为代表梁扑动的三自由度非线性系统,再加上代表 NIPPF 控制器的一阶和二阶滤波器。通过对线性化系统模型进行扰动分析,作者获得了带有控制器的自主系统的解析解。本研究旨在减小非线性动态系统的振动幅度,特别是在发生 1:1 内部共振时。利用 Routh-Hurwitz 准则来评估系统的稳定性。此外,频率响应曲线(FRC)在一定参数值范围内表现出对称性。研究结果表明,在与不同控制器进行比较后,振动抑制效果与 NIPPF 控制信号的乘积直接相关。使用四阶 Runge-Kutta 方法进行的数值模拟验证了分析解,并证明了系统的振幅响应。分析和数值结果之间的紧密相关性凸显了所建议方法的准确性和可靠性。
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引用次数: 0
Three-Dimensional Lorentz-Invariant Velocities 三维洛伦兹不变速度
Pub Date : 2024-09-02 DOI: 10.3390/sym16091133
James M. Hill
Lorentz invariance underlies special relativity, and the energy formula and relative velocity formula are well known to be invariant under a Lorentz transformation. Here, we determine the functional forms in terms of four arbitrary functions for those three dimensional velocity fields that are automatically invariant under the most general fully three-dimensional Lorentz transformation. For general three-dimensional motion, using rectangular Cartesian coordinates (x,y,z), we determine the first-order partial differential equations for the three velocity components u(x,y,z,t), v(x,y,z,t) and w(x,y,z,t) in the x−, y− and z−directions respectively. These partial differential equations and the associated partial differential relations connecting energy and momentum are fully compatible with the Lorentz-invariant energy–momentum relations and appear not to have been given previously in the literature. We determine the spatial and temporal dependence of the functional forms for those three-dimensional velocity fields that are automatically invariant under three-dimensional Lorentz transformations. An interesting special case gives rise to families of particle paths for which the magnitude of the velocity is the speed of light. This is indicative of the abundant possibilities existing in the “fast lane”.
洛伦兹不变性是狭义相对论的基础,众所周知,能量公式和相对速度公式在洛伦兹变换下是不变的。在这里,我们确定了在最一般的完全三维洛伦兹变换下自动不变的三维速度场的四个任意函数的函数形式。对于一般的三维运动,使用矩形直角坐标 (x,y,z),我们分别确定了 x、y 和 z 方向上三个速度分量 u(x,y,z,t)、v(x,y,z,t) 和 w(x,y,z,t) 的一阶偏微分方程。这些偏微分方程以及连接能量和动量的相关偏微分关系与洛伦兹不变的能量-动量关系完全吻合,似乎是以前文献中没有给出过的。我们确定了在三维洛伦兹变换下自动不变的三维速度场的函数形式的空间和时间依赖性。一个有趣的特例是,粒子路径的速度大小是光速。这表明在 "快车道 "上存在着丰富的可能性。
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引用次数: 0
The Relationship between Cardiomyocyte Action Potentials and Ion Concentrations: Machine Learning Prediction Modeling and Analysis of Spontaneous Spiral Wave Generation Mechanisms 心肌细胞动作电位与离子浓度的关系:自发螺旋波产生机制的机器学习预测建模与分析
Pub Date : 2024-09-02 DOI: 10.3390/sym16091136
Jing Bai, Chunfu Zhang, Yanchun Liang, Adriano Tavares, Lidong Wang, Xue Gu, Ziyao Meng
The changes in cardiomyocyte action potentials are related to variations in intra- and extracellular ion concentrations. Abnormal ion concentrations can lead to irregular action potentials, subsequently affecting wave propagation in myocardial tissue and potentially resulting in the formation of spiral waves. Therefore, timely monitoring of ion concentration changes is essential. This study presents a novel machine learning classification model that predicts ion concentration changes based on action potential variation data. We conducted simulations using a single-cell model, generating a dataset of 850 action potential variations corresponding to different ion concentration changes. The model demonstrated excellent predictive performance, achieving an accuracy of 0.988 on the test set. Additionally, the causes of spontaneous spiral wave generation in the heart are insufficiently studied. This study presents a new mechanism whereby changes in extracellular potassium ion concentration leads to the spontaneous generation of spiral waves. By constructing composite myocardial tissue containing both myocardial and fibroblast cells, we observed that variations in extracellular potassium ion concentration can either trigger or inhibit cardiomyocyte excitation. We developed three tissue structures, and by appropriately adjusting the extracellular potassium ion concentration, we observed the spontaneous generation of single spiral waves, symmetrical spiral wave pairs, and asymmetrical double spiral waves.
心肌细胞动作电位的变化与细胞内外离子浓度的变化有关。异常的离子浓度会导致不规则的动作电位,进而影响波在心肌组织中的传播,并可能形成螺旋波。因此,及时监测离子浓度变化至关重要。本研究提出了一种新型机器学习分类模型,可根据动作电位变化数据预测离子浓度变化。我们使用单细胞模型进行了模拟,生成了与不同离子浓度变化相对应的 850 个动作电位变化数据集。该模型表现出卓越的预测性能,在测试集上达到了 0.988 的准确率。此外,对心脏自发螺旋波产生的原因研究不足。本研究提出了细胞外钾离子浓度变化导致螺旋波自发产生的新机制。通过构建包含心肌细胞和成纤维细胞的复合心肌组织,我们观察到细胞外钾离子浓度的变化可以触发或抑制心肌细胞的兴奋。我们开发了三种组织结构,通过适当调节细胞外钾离子浓度,我们观察到了单螺旋波、对称螺旋波对和不对称双螺旋波的自发产生。
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引用次数: 0
Invariant Sets, Global Dynamics, and the Neimark–Sacker Bifurcation in the Evolutionary Ricker Model 进化里克尔模型中的不变集、全局动力学和奈马克-萨克分岔
Pub Date : 2024-09-02 DOI: 10.3390/sym16091139
Rafael Luís, Brian Ryals
In this paper, we study the local, global, and bifurcation properties of a planar nonlinear asymmetric discrete model of Ricker type that is derived from a Darwinian evolution strategy based on evolutionary game theory. We make a change of variables to both reduce the number of parameters as well as bring symmetry to the isoclines of the mapping. With this new model, we demonstrate the existence of a forward invariant and globally attracting set where all the dynamics occur. In this set, the model possesses two symmetric fixed points: the origin, which is always a saddle fixed point, and an interior fixed point that may be globally asymptotically stable. Moreover, we observe the presence of a supercritical Neimark–Sacker bifurcation, a phenomenon that is not present in the original non-evolutionary model.
本文研究了基于进化博弈论的达尔文进化策略衍生出的 Ricker 型平面非线性非对称离散模型的局部、全局和分岔特性。我们改变了变量,既减少了参数数量,又使映射的等值线具有对称性。通过这个新模型,我们证明了存在一个前向不变且具有全局吸引力的集合,所有动态都发生在这个集合中。在这个集合中,模型有两个对称的固定点:一个是原点,它总是一个鞍形固定点;另一个是内部固定点,它可能是全局渐近稳定的。此外,我们还观察到了超临界 Neimark-Sacker 分岔的存在,而这种现象在原始的非演化模型中是不存在的。
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引用次数: 0
The Optimal Experimental Design for Exponentiated Frech’et Lifetime Products 幂次弗雷希等寿命产品的最佳实验设计
Pub Date : 2024-09-02 DOI: 10.3390/sym16091132
Shu-Fei Wu
In many manufacturing industries, the lifetime performance index CL is utilized to assess the manufacturing process performance for products following some lifetime distributions and subjecting them to progressive type I interval censoring. This paper aims to explore the sampling design required to achieve a specified level of significance and test power for products with lifetimes following the Exponentiated Frech’et distribution. Since lifetime distribution is an asymmetrical probability distribution, this investigation is related to the topic of asymmetrical probability distributions and applications in various fields. When the termination time is fixed but the number of intervals is variable, the optimal number of inspection intervals and sample sizes yielding the minimized total experimental costs are determined and tabulated. When the termination time is varying, the optimal number of inspection intervals, sample sizes, and equal interval lengths achieving the minimum total experimental costs are determined and tabulated. Optimal parameter values are displayed in tabular form for feasible applications for users. Additionally, a practical example is provided to illustrate how this sampling design can be used to collect data by using the optimal setup of parameters, followed by a testing procedure to assess the capability of the production process.
在许多制造业中,寿命性能指标 CL 被用来评估遵循某些寿命分布的产品的制造过程性能,并对其进行渐进式 I 型区间删减。本文旨在探讨对于寿命服从幂级数弗莱赫等分布的产品,为达到特定显著性水平和测试功率所需的抽样设计。由于寿命分布是一种非对称概率分布,因此本研究与非对称概率分布的主题及在各个领域的应用相关。当终止时间固定而间隔次数可变时,确定并列表说明了产生最小总实验成本的最佳检查间隔次数和样本大小。当终止时间变化时,可确定并列表显示检查间隔的最佳次数、样本大小和等间隔长度,从而使实验总成本最小。最佳参数值以表格形式显示,供用户进行可行的应用。此外,还提供了一个实际例子,说明如何利用最佳参数设置来收集数据,然后通过测试程序来评估生产过程的能力。
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引用次数: 0
Structural and Spectral Properties of Chordal Ring, Multi-Ring, and Mixed Graphs 弦环、多环和混合图的结构和谱特性
Pub Date : 2024-09-02 DOI: 10.3390/sym16091135
M. A. Reyes, C. Dalfó, M. A. Fiol
The chordal ring (CR) graphs are a well-known family of graphs used to model some interconnection networks for computer systems in which all nodes are in a cycle. Generalizing the CR graphs, in this paper, we introduce the families of chordal multi-ring (CMR), chordal ring mixed (CRM), and chordal multi-ring mixed (CMRM) graphs. In the case of mixed graphs, we can have edges (without direction) and arcs (with direction). The chordal ring and chordal ring mixed graphs are bipartite and 3-regular. They consist of a number r (for r≥1) of (undirected or directed) cycles with some edges (the chords) joining them. In particular, for CMR, when r=1, that is, with only one undirected cycle, we obtain the known families of chordal ring graphs. Here, we used plane tessellations to represent our chordal multi-ring graphs. This allowed us to obtain their maximum number of vertices for every given diameter. Additionally, we computationally obtained their minimum diameter for any value of the number of vertices. Moreover, when seen as a lift graph (also called voltage graph) of a base graph on Abelian groups, we obtained closed formulas for the spectrum, that is, the eigenvalue multi-set of its adjacency matrix.
弦环图(CR)是一个著名的图族,用于模拟计算机系统中所有节点都在一个周期内的某些互连网络。在本文中,我们对 CR 图进行了归纳,引入了弦多环(CMR)、弦环混合(CRM)和弦多环混合(CMRM)图族。在混合图中,我们可以有边(无方向)和弧(有方向)。弦环图和弦环混合图是双方形和三规则图。它们由若干个 r(r≥1)的(无向或有向)循环和连接它们的一些边(弦)组成。特别是对于 CMR,当 r=1 时,即只有一个无向循环时,我们可以得到已知的弦环图族。在这里,我们使用平面方格来表示弦多环图。这样,我们就能获得每个给定直径下的最大顶点数。此外,我们还通过计算获得了任何顶点数量值的最小直径。此外,如果将其视为阿贝尔群上基图的提升图(也称为电压图),我们还获得了频谱的封闭公式,即其邻接矩阵的特征值多集。
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引用次数: 0
Sharp Results for a New Class of Analytic Functions Associated with the q-Differential Operator and the Symmetric Balloon-Shaped Domain 与 q 微分算子和对称气球形域相关的一类新解析函数的尖锐结果
Pub Date : 2024-09-02 DOI: 10.3390/sym16091134
Adeel Ahmad, Jianhua Gong, Akhter Rasheed, Saqib Hussain, Asad Ali, Zeinebou Cheikh
In our current study, we apply differential subordination and quantum calculus to introduce and investigate a new class of analytic functions associated with the q-differential operator and the symmetric balloon-shaped domain. We obtain sharp results concerning the Maclaurin coefficients the second and third-order Hankel determinants, the Zalcman conjecture, and its generalized conjecture for this newly defined class of q-starlike functions with respect to symmetric points.
在当前的研究中,我们应用微分从属关系和量子微积分引入并研究了一类与 q 微分算子和对称气球形域相关的新解析函数。对于这一类新定义的 q 星状函数,我们获得了关于对称点的麦克劳林系数、二阶和三阶汉克尔行列式、扎尔克曼猜想及其广义猜想的尖锐结果。
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引用次数: 0
A Unified Hardware Design for Multiplication, Division, and Square Roots Using Binary Logarithms 使用二进制对数进行乘法、除法和平方根运算的统一硬件设计
Pub Date : 2024-09-02 DOI: 10.3390/sym16091138
Dat Ngo, Siyeon Han, Bongsoon Kang
Multiplication, division, and square root operations introduce significant challenges in digital signal processing (DSP) systems, traditionally requiring multiple operations that increase execution time and hardware complexity. This study presents a novel approach that leverages binary logarithms to perform these operations using only addition, subtraction, and shifts, enabling a unified hardware implementation—a marked departure from conventional methods that handle these operations separately. The proposed design, involving logarithm and antilogarithm calculations, exhibits an algebraically symmetrical pattern that further optimizes the processing flow. Additionally, this study introduces innovative log-domain correction terms specifically designed to minimize computation errors—a critical improvement over existing methods that often struggle with precision. Compared to standard hardware implementations, the proposed design significantly reduces hardware resource utilization and power consumption while maintaining high operational frequency.
乘法、除法和平方根运算给数字信号处理(DSP)系统带来了巨大挑战,传统上需要进行多种运算,从而增加了执行时间和硬件复杂性。本研究提出了一种新方法,利用二进制对数来执行这些运算,只需加法、减法和移位,从而实现了统一的硬件实现--这与分别处理这些运算的传统方法大相径庭。拟议的设计涉及对数和反对数计算,呈现出一种代数对称模式,进一步优化了处理流程。此外,这项研究还引入了创新的对数域修正项,专门用于最大限度地减少计算误差,这是对现有方法的重要改进,因为现有方法在精度方面往往存在困难。与标准硬件实现相比,所提出的设计大大降低了硬件资源利用率和功耗,同时保持了较高的运行频率。
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引用次数: 0
Existence and Uniqueness of Solution Represented as Fractional Power Series for the Fractional Advection–Dispersion Equation 以分数幂级数表示的分数平流-分散方程的解的存在性和唯一性
Pub Date : 2024-09-02 DOI: 10.3390/sym16091137
Alexandru-Nicolae Dimache, Ghiocel Groza, Marilena Jianu, Iulian Iancu
The fractional advection–dispersion equation is used in groundwater hydrology for modeling the movements of contaminants/solute particles along with flowing groundwater at the seepage velocity in porous media. This model is used for the prediction of the transport of nonreactive dissolved contaminants in groundwater. This paper establishes the existence and the uniqueness of solutions represented as fractional bi-variate power series of some initial-value problems and boundary-value problems for the fractional advection–dispersion equation. Moreover, a method to approximate the solutions using fractional polynomials in two variables and to evaluate the errors in a suitable rectangle is designed. Illustrative examples showing the applicability of the theoretical results are presented.
在地下水水文学中,分数平流-分散方程用于模拟多孔介质中污染物/固态颗粒随流动地下水以渗流速度的运动。该模型用于预测非反应性溶解污染物在地下水中的迁移。本文确定了分数平流-扩散方程的一些初值问题和边界值问题的分数双变量幂级数解的存在性和唯一性。此外,还设计了一种使用双变量分数多项式近似求解的方法,以及在合适的矩形范围内评估误差的方法。此外,还介绍了显示理论结果适用性的示例。
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引用次数: 0
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Symmetry
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