Symmetry最新文献_第8页

Spectral Properties of Dual Unit Gain Graphs 双单元增益图的频谱特性

Symmetry Pub Date : 2024-09-03 DOI: 10.3390/sym16091142

Chunfeng Cui, Yong Lu, Liqun Qi, Ligong Wang

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

Symmetry Pub Date : 2024-09-03 DOI: 10.3390/sym16091143

Khalid Alluhydan, Yasser A. Amer, Ashraf Taha EL-Sayed, Marwa Abdelaziz EL-Sayed

{"title":"The Impact of the Nonlinear Integral Positive Position Feedback (NIPPF) Controller on the Forced and Self-Excited Nonlinear Beam Flutter Phenomenon","authors":"Khalid Alluhydan, Yasser A. Amer, Ashraf Taha EL-Sayed, Marwa Abdelaziz EL-Sayed","doi":"10.3390/sym16091143","DOIUrl":"https://doi.org/10.3390/sym16091143","url":null,"abstract":"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.","PeriodicalId":501198,"journal":{"name":"Symmetry","volume":"260 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Three-Dimensional Lorentz-Invariant Velocities 三维洛伦兹不变速度

Symmetry Pub Date : 2024-09-02 DOI: 10.3390/sym16091133

James M. Hill

{"title":"Three-Dimensional Lorentz-Invariant Velocities","authors":"James M. Hill","doi":"10.3390/sym16091133","DOIUrl":"https://doi.org/10.3390/sym16091133","url":null,"abstract":"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”.","PeriodicalId":501198,"journal":{"name":"Symmetry","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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

Symmetry Pub Date : 2024-09-02 DOI: 10.3390/sym16091136

Jing Bai, Chunfu Zhang, Yanchun Liang, Adriano Tavares, Lidong Wang, Xue Gu, Ziyao Meng

{"title":"The Relationship between Cardiomyocyte Action Potentials and Ion Concentrations: Machine Learning Prediction Modeling and Analysis of Spontaneous Spiral Wave Generation Mechanisms","authors":"Jing Bai, Chunfu Zhang, Yanchun Liang, Adriano Tavares, Lidong Wang, Xue Gu, Ziyao Meng","doi":"10.3390/sym16091136","DOIUrl":"https://doi.org/10.3390/sym16091136","url":null,"abstract":"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.","PeriodicalId":501198,"journal":{"name":"Symmetry","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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

Symmetry Pub Date : 2024-09-02 DOI: 10.3390/sym16091139

Rafael Luís, Brian Ryals

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

Symmetry Pub Date : 2024-09-02 DOI: 10.3390/sym16091132

Shu-Fei Wu

{"title":"The Optimal Experimental Design for Exponentiated Frech’et Lifetime Products","authors":"Shu-Fei Wu","doi":"10.3390/sym16091132","DOIUrl":"https://doi.org/10.3390/sym16091132","url":null,"abstract":"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.","PeriodicalId":501198,"journal":{"name":"Symmetry","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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

Symmetry Pub Date : 2024-09-02 DOI: 10.3390/sym16091135

M. A. Reyes, C. Dalfó, M. A. Fiol

{"title":"Structural and Spectral Properties of Chordal Ring, Multi-Ring, and Mixed Graphs","authors":"M. A. Reyes, C. Dalfó, M. A. Fiol","doi":"10.3390/sym16091135","DOIUrl":"https://doi.org/10.3390/sym16091135","url":null,"abstract":"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.","PeriodicalId":501198,"journal":{"name":"Symmetry","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142209027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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

Symmetry Pub Date : 2024-09-02 DOI: 10.3390/sym16091134

Adeel Ahmad, Jianhua Gong, Akhter Rasheed, Saqib Hussain, Asad Ali, Zeinebou Cheikh

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

Symmetry Pub Date : 2024-09-02 DOI: 10.3390/sym16091138

Dat Ngo, Siyeon Han, Bongsoon Kang

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

Symmetry Pub Date : 2024-09-02 DOI: 10.3390/sym16091137

Alexandru-Nicolae Dimache, Ghiocel Groza, Marilena Jianu, Iulian Iancu

引用次数: 0