{"title":"Enhancing sparse identification of nonlinear dynamics with Earth-Mover distance and group similarity.","authors":"Donglin Liu, Alexandros Sopasakis","doi":"10.1063/5.0214404","DOIUrl":"https://doi.org/10.1063/5.0214404","url":null,"abstract":"<p><p>The sparse identification of nonlinear dynamics (SINDy) algorithm enables us to discover nonlinear dynamical systems purely from data but is noise-sensitive, especially in low-data scenarios. In this work, we introduce an advanced method that integrates group sparsity thresholds with Earth Mover's distance-based similarity measures in order to enhance the robustness of identifying nonlinear dynamics and the learn functions of dynamical systems governed by parametric ordinary differential equations. This novel approach, which we call group similarity SINDy (GS-SINDy), not only improves interpretability and accuracy in varied parametric settings but also isolates the relevant dynamical features across different datasets, thus bolstering model adaptability and relevance. Applied to several complex systems, including the Lotka-Volterra, Van der Pol, Lorenz, and Brusselator models, GS-SINDy demonstrates consistently enhanced accuracy and reliability, showcasing its effectiveness in diverse applications.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143662916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fast-slow dynamics and spike organization in the electromechanical gyrostat system: Unveiling the intricacies of shrimp structures.","authors":"Xu-Ping Zhao, Li-Ying Xing, Jian-She Gao","doi":"10.1063/5.0233740","DOIUrl":"https://doi.org/10.1063/5.0233740","url":null,"abstract":"<p><p>This paper investigates the nonlinear dynamics of an electromechanical gyrostat system, focusing on the timescale characteristics of the system's fast variables. Through three kinds of complementary stability diagrams, the complex dynamical structures, particularly the formation and organization of the well-known \"shrimp\" structures, are unfolded in the parameter space. The research identifies significant differences in the rates of the system's fast variables, which directly affect the distribution of spikes and explain the diversity in the internal spike distribution of shrimps. These findings provide new insights and a theoretical foundation for understanding and controlling complex behaviors in nonlinear dynamical systems. This work is also developed further on the foundation of the pioneering work by Professor Jason A. C. Gallas, as a tribute to his outstanding contributions to the field of nonlinear dynamics.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143669181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Power Levy motion. II. Evolution.","authors":"Iddo Eliazar","doi":"10.1063/5.0251341","DOIUrl":"https://doi.org/10.1063/5.0251341","url":null,"abstract":"<p><p>This is the second part of a pair of papers that introduce and explore power Levy motion (PLM). The first part constructed PLM and explained its emergence and rationale. Taking on a \"diffusion perspective,\" the first part addressed key facets and features of PLM. Taking on an \"evolution perspective,\" this part continues the investigation of PLM and addresses its following facets and features: Markov dynamics and propagator; simulation; increments' conditional distributions; persistence and anti-persistence; power-law asymptotics and Taylor's law; integral representation; Langevin dynamics and stochastic differential equation; center-reversion and center-repulsion; decreasing and increasing volatility; Lamperti transformation and Ornstein-Uhlenbeck representation. This pair of papers establishes PLM as a potent and compelling anomalous-diffusion model and presents a comprehensive exposition of PLM.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143699856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Power Levy motion. I. Diffusion.","authors":"Iddo Eliazar","doi":"10.1063/5.0251337","DOIUrl":"https://doi.org/10.1063/5.0251337","url":null,"abstract":"<p><p>Recently introduced and explored, power Brownian motion (PBM) is a versatile generalization of Brownian motion: it is Markovian on the one hand and it displays a variety of anomalous-diffusion behaviors on the other hand. Brownian motion is the universal scaling-limit of finite-variance random walks. Shifting from the finite-variance realm to the infinite-variance realm, the counterpart of Brownian motion is Levy motion: the stable and symmetric Levy process. This pair of papers introduces and explores power Levy motion (PLM), which is to Levy motion what PBM is to Brownian motion. This first part of the pair constructs PLM and explains its emergence and rationale. Taking on a \"diffusion perspective,\" this part addresses the following facets and features of PLM: increments and their Fourier structure, selfsimilarity and Hurst exponent, sub-diffusion and super-diffusion, aging and anti-aging, and Holder exponent. Taking on an \"evolution perspective,\" the second part will continue the investigation of PLM.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143699853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianbo Wang, Haoxing He, Ping Li, Zhanwei Du, Xiaoke Xu
{"title":"Epidemic spread dynamics in multilayer networks: Probing the impact of information outbreaks and reception games.","authors":"Jianbo Wang, Haoxing He, Ping Li, Zhanwei Du, Xiaoke Xu","doi":"10.1063/5.0236359","DOIUrl":"https://doi.org/10.1063/5.0236359","url":null,"abstract":"<p><p>The co-evolution of epidemic and information spread within multilayer networks is a current hot topic in network science. During epidemic outbreaks, the accompanying information exhibits both outbreak and reception game behaviors; yet, these complex phenomena have been scarcely addressed in existing research. In this paper, we model information outbreaks using activated individuals who transmit messages to their neighbors, while also considering the game behaviors of information receivers. By focusing on these two factors, we establish a multilayer network model featuring both information outbreaks and reception games. Employing the microscopic Markov chain method, we analyze the propagation dynamics within this network and derive epidemic thresholds, corroborating these results with Monte Carlo simulations. Our findings indicate that information outbreaks suppress epidemic outbreaks, whereas increased costs of information reception promote epidemic spread. Smooth information dissemination further inhibits the transmission of the epidemic. Additionally, we observe that heterogeneity in the network structure between the virtual and physical layers reduces the ultimate scale of epidemic infection, with the virtual layer exerting a more substantial influence. These insights are crucial for elucidating the co-evolutionary mechanisms of spread within multilayer networks and for developing effective epidemic prevention and control strategies.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143572061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Optimizing self-organized topology of recurrence-based complex networks.","authors":"Conggai Li, Joseph C S Lai, Sebastian Oberst","doi":"10.1063/5.0249500","DOIUrl":"https://doi.org/10.1063/5.0249500","url":null,"abstract":"<p><p>Networks and graphs have emerged as powerful tools to model and analyze nonlinear dynamical systems. By constructing an adjacency matrix from recurrence networks, it is possible to capture critical structural and geometric information about the underlying dynamics of a time series. However, randomization of data often raises concerns about the potential loss of deterministic relationships. Here, in using the spring-electrical-force model, we demonstrate that by optimizing the distances between randomized points through minimizing an entropy-related energy measure, the deterministic structure of the original system is not destroyed. This process allows us to approximate the time series shape and correct the phase, effectively reconstructing the initial invariant set and attracting dynamics of the system. Our approach highlights the importance of adjacency matrices derived from recurrence plots, which preserve crucial information about the nonlinear dynamics. By using recurrence plots and the entropy of diagonal line lengths and leveraging the Kullback-Leibler divergence as a relative entropic measure, we fine-tune the parameters and initial conditions for recurrence plots, ensuring an optimal representation of the system's dynamics. Through the integration of network geometry and energy minimization, we show that data-driven graphs can self-organize to retain and regenerate the fundamental features of the time series, including its phase space structures. This study underscores the robustness of recurrence networks as a tool for analyzing nonlinear systems and demonstrates that randomization, when guided by informed optimization, does not erase deterministic relationships, opening new avenues for reconstructing dynamical systems from observational data.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143572195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Dynamic evolution in multi-player networked trust games with graded punishment.","authors":"Juan Wang, Zhuo Liu, Yan Xu, Xiaopeng Li","doi":"10.1063/5.0256342","DOIUrl":"https://doi.org/10.1063/5.0256342","url":null,"abstract":"<p><p>Trust holds a pivotal position in contemporary society. Yet, the question of how to elevate and sustain trust among selfish individuals poses a formidable challenge. To delve into this issue, we incorporate a graded punishment strategy into a networked N-player trust game, aiming to observe the progression of trust-related behavior. Within this game framework, punishers uphold a certain degree of trust among the participants by incurring an extra expense to exclude those who betray trust. By conducting numerous Monte Carlo simulation experiments, we uncover that the graded punishment strategy can effectively curtail untrustworthy conduct to a significant degree, potentially even eliminating such behavior, thereby fostering an improvement in the overall trust level within the population. However, to effectively deploy this strategy, it is imperative to strike a balance between the penalty cost and the penalty amount, ensuring that the natural evolution of the system is not unduly disrupted. This balance is crucial for preserving the stability and sustainability of the system while safeguarding trust. Broadly speaking, our study offers fresh insights and approaches for enhancing and maintaining trust in the networked society, while also highlighting the avenues and challenges for future research, particularly in the realm of applying graded punishment strategies.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Sensitivities in complex-time flows: Phase transitions, Hamiltonian structure, and differential geometry.","authors":"Dirk Lebiedz, Johannes Poppe","doi":"10.1063/5.0245642","DOIUrl":"https://doi.org/10.1063/5.0245642","url":null,"abstract":"<p><p>Reminiscent of physical phase transition separatrices divides the phase space of dynamical systems with multiple equilibria into regions of distinct flow behavior and asymptotics. We introduce complex time in order to study corresponding Riemann surface solutions of holomorphic and meromorphic flows, explicitly solve their sensitivity differential equation, and identify a related Hamiltonian structure and an associated geometry in order to study separatrix properties. As an application, we analyze the complex-time Newton flow of Riemann's ξ-function on the basis of a compactly convergent polynomial approximation of its Riemann surface solution defined as zero set of polynomials, e.g., algebraic curves over C (in the complex projective plane, respectively), that is closely related to a complex-valued Hamiltonian system. Its geometric properties might contain information on the global separatrix structure and the root location of ξ and ξ'.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Structure-and-embedding-based centrality on network fragility in hypergraphs.","authors":"Lanlan Chang, Tian Qiu, Guang Chen","doi":"10.1063/5.0232539","DOIUrl":"https://doi.org/10.1063/5.0232539","url":null,"abstract":"<p><p>Revealing the critical nodes is crucial to maintain network safety. Various methods have been proposed to identify the vital nodes and, recently, have been generalized from ordinary networks to hypergraphs. However, many existing methods did not consider both the hypergraph structure and embedding. In this article, we investigate two topological structural centralities by considering the common nodes and the common hyperedges and a hypergraph embedding centrality based on representation learning. Four improved centralities are proposed by considering only the node embedding, and the joint of the node embedding and hypergraph structural common nature. The network fragility is investigated for six real datasets. The proposed methods are found to outperform the baseline methods in five hypergraphs, and incorporating the embedding feature into the structural centralities can greatly improve the performance of the single structure-based centralities. The obtained results are heuristically understood by a similarity analysis of the node embeddings.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jun Huang, Huijuan Dong, Na Li, Yizhou Li, Jing Zhu, Xiaowei Li, Bin Hu
{"title":"Amplitude-sensitive permutation entropy: A novel complexity measure incorporating amplitude variation for physiological time series.","authors":"Jun Huang, Huijuan Dong, Na Li, Yizhou Li, Jing Zhu, Xiaowei Li, Bin Hu","doi":"10.1063/5.0245842","DOIUrl":"https://doi.org/10.1063/5.0245842","url":null,"abstract":"<p><p>Physiological time series, such as electrocardiogram (ECG) and electroencephalogram (EEG) data, are instrumental in capturing the critical dynamics of biological systems, including cardiovascular behavior and neural activity. The traditional permutation entropy (PE) methods effectively analyze the complexity of such signals but often overlook amplitude variations, which encode essential information about physiological states and pathological conditions. This paper introduces amplitude-sensitive permutation entropy (ASPE), a novel method that enhances PE by integrating amplitude information through the coefficient of variation as a weighting factor. Unlike the existing approaches that may overemphasize or underutilize amplitude changes, ASPE's balanced weighting strategy captures both the average level and dispersion of data, preserving the overall signal complexity. To validate ASPE's effectiveness, we conducted simulation experiments and applied them to two real-world datasets: an EEG dataset of epileptic seizures and an ECG dataset of arrhythmias. In simulations, ASPE demonstrated superior sensitivity to amplitude changes, outperforming the five existing PE methods in identifying dynamic variations accurately. In the physiological datasets, ASPE distinguished disease states more effectively, accurately identifying seizure phases and arrhythmic patterns. These results highlight ASPE's potential as a robust tool for analyzing physiological data with complex amplitude dynamics, offering a more comprehensive assessment of signal behavior and disease states than the current methods.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 3","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143603930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}