Siyuan Chang, Wei Ma, Min Ye, Joseph Páez Chávez, Yelin Li, Yuchuan Ma, Jiale Zhang
{"title":"Delayed feedback control and parameter continuation of multistability in a nonsmooth hydraulic rock drill model.","authors":"Siyuan Chang, Wei Ma, Min Ye, Joseph Páez Chávez, Yelin Li, Yuchuan Ma, Jiale Zhang","doi":"10.1063/5.0268836","DOIUrl":"https://doi.org/10.1063/5.0268836","url":null,"abstract":"<p><p>In response to the complex multistable behavior observed in hydraulic rock drills during the drilling process, this study first establishes a four-degree-of-freedom physical model based on dry friction rock mechanics theory. The motion trajectory is classified into three states: non-viscous, impact viscous, and buffer viscous. Using the impact frequency ω as the bifurcation parameter, multistable attractors p0q1 and p1q2 are identified in the system when ω = 9. To control the multistability, a delayed feedback control method is applied, in which the infinite-dimensional delay differential equations are approximated by finite-dimensional ordinary differential equations. The reliability of this approximation is validated through a distance function. When the control gain K = 9 and the delay time τd = 0.35, both attractors p0q1 and p1q2 are successfully converted into a single p0q1 attractor. Next, the pseudo-arclength continuation method and Floquet theory are employed to investigate parameter continuation and parameter domains. The period-doubling bifurcation points PD1 and PD2 divide the parameter space of K and τd into three distinct regions. Crossing these regions induces a supercritical period-doubling bifurcation. For constant K, a smaller τd leads to an increased number of collisions and periodic motions in the system. Simulation results demonstrate that by tuning the delay parameters, the multistability during the drilling process can be effectively controlled, thereby enhancing drilling efficiency and stability. Finally, rock drilling experiments confirm the validity of the model and the presence of multistability. When drilling into rocks with high hardness and brittleness, multistable motions are more likely to occur.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144315999","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":"Optimal control for phase locking of synchronized oscillator populations via dynamical reduction techniques.","authors":"Narumi Fujii, Hiroya Nakao","doi":"10.1063/5.0275374","DOIUrl":"https://doi.org/10.1063/5.0275374","url":null,"abstract":"<p><p>We present a framework for controlling the collective phase of a system of coupled oscillators described by the Kuramoto model under the influence of a periodic external input by combining the methods of dynamical reduction and optimal control. We employ the Ott-Antonsen ansatz and phase-amplitude reduction theory to derive a pair of one-dimensional equations for the collective phase and amplitude of mutually synchronized oscillators. We then use optimal control theory to derive the optimal input for controlling the collective phase based on the phase equation and evaluate the effect of the control input on the degree of mutual synchrony using the amplitude equation. We setup an optimal control problem for the system to quickly resynchronize with the periodic input after a sudden phase shift in the periodic input, a situation similar to jet lag, and demonstrate the validity of the framework through numerical simulations.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144282701","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}
S Sinet, R Bastiaansen, C Kuehn, A S von der Heydt, H A Dijkstra
{"title":"Approximating the bifurcation diagram of weakly and strongly coupled leading-following systems.","authors":"S Sinet, R Bastiaansen, C Kuehn, A S von der Heydt, H A Dijkstra","doi":"10.1063/5.0269773","DOIUrl":"10.1063/5.0269773","url":null,"abstract":"<p><p>The potential of dynamical systems to undergo bifurcation-induced tipping has received much attention recently in climate and ecology research. In particular, such systems can form an intricate interacting network, creating the possibility of cascading critical transitions in which tipping of one element results in the tipping of another. In this paper, we focus on unidirectionally coupled scalar subsystems in which one component is driven by a polynomial equation. We investigate such interacting systems beyond the so-far used setting of linearly interacting bistable subsystems. In these cases, we show how the bifurcation diagram of the coupled system can be approximated using asymptotic methods, starting from the simpler bifurcation diagram of the decoupled problems. We study the limits in which the coupling is weak or strong, yielding approximations of the equilibrium branches and their stability. Those results are illustrated using conceptual models for the ocean circulation driven by wind and density and for the interacting ocean circulation and Amazon rainforest.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144336371","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":"First passage properties of d-dimensional finite combs with different growth modes.","authors":"Yuan Zhu, Zhenhua Yuan, Junhao Peng","doi":"10.1063/5.0273216","DOIUrl":"https://doi.org/10.1063/5.0273216","url":null,"abstract":"<p><p>The study of first-passage phenomena in comb structures represents a fundamental research topic with broad applications across physics, chemistry, biology, materials science, and engineering. In this work, we present an analytical framework for evaluating both the mean trapping time and global-mean first-passage time (GFPT) for random walks on general d-dimensional (d≥1) finite comb networks. The GFPT, being a crucial metric for quantifying transport efficiency in networked systems, receives particular attention in our study. Through systematic analysis, we characterize the scaling behavior of GFPT with respect to network size N under various growth modes. Our principal findings reveal that in d-dimensional (d≥1) finite combs, the GFPT follows a power-law scaling Nγ, where the exponent γ∈[1+1d,2]. Notably, we demonstrate that for any target exponent γ within this interval, there exists a corresponding network growth mode that realizes GFPT∼Nγ. This discovery establishes a direct methodology for controlling the transport efficiency scaling exponent γ through strategic selection of network growth patterns.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144246718","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":"Impact of internal noise on convolutional neural networks.","authors":"I D Kolesnikov, N Semenova","doi":"10.1063/5.0275670","DOIUrl":"https://doi.org/10.1063/5.0275670","url":null,"abstract":"<p><p>In this paper, we investigate the impact of noise on a simplified trained convolutional network. The types of noise studied originate from real optical implementation of a neural network, but we generalize these types to enhance the applicability of our findings on a broader scale. The noise types considered include additive and multiplicative noise, which relate to how noise affects individual neurons, as well as correlated and uncorrelated noise, which pertains to the influence of noise across one layer. We demonstrate that the propagation of uncorrelated noise primarily depends on the statistical properties of the connection matrices. Specifically, the mean value of the connection matrix following the layer impacted by noise governs the propagation of correlated additive noise, while the mean of its square contributes to the accumulation of uncorrelated noise. Additionally, we propose an analytical assessment of the noise level in the network's output signal, which shows a strong correlation with the results of numerical simulations.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144246720","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":"Chaos, dynamic trapping, and transport of swimming microbes in a vortex chain flow.","authors":"Nghia Le, Thomas H Solomon","doi":"10.1063/5.0270869","DOIUrl":"https://doi.org/10.1063/5.0270869","url":null,"abstract":"<p><p>We present experiments on chaotic motion of self-propelled (active) particles in a time-independent, two-dimensional vortex chain flow. We track Tetraselmis microbes and calculate the variance of a spreading distribution of these microbes in the flow. For small non-dimensional swimming speed v0, we find subdiffusion with variance ⟨x2⟩∼tγ with γ<1; transport is diffusive (γ=1) for larger v0. Subdiffusion for small v0 is due to dynamic trapping of microbes to islands of ordered trajectories surrounded by a sea of chaotic motion; these islands disappear for larger v0. We calculate Lagrangian-averaged trajectories (LATs) from the experimental data and use the LATs to measure trapping time probability distributions P(t). We find regimes with P(t)∼t-ν with ν<2 for small v0, consistent with the measured subdiffusion.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144233357","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}
Vijay Yadav, Madhu Priya, Manish Dev Shrimali, Prabhat K Jaiswal
{"title":"Graph neural network for prediction of phase-ordering kinetics.","authors":"Vijay Yadav, Madhu Priya, Manish Dev Shrimali, Prabhat K Jaiswal","doi":"10.1063/5.0273728","DOIUrl":"https://doi.org/10.1063/5.0273728","url":null,"abstract":"<p><p>The study of evolving structures and patterns has always been a central point in understanding the universe, ranging from molecular processes at the nanoscale to the galaxies. Recent approaches have adopted machine learning techniques to study these dynamical systems. Here, we implemented the graph neural network to predict the spatiotemporal pattern formation in the ordering of a ferromagnet (nonconserved system) and phase separation of a binary mixture (conserved system). We show that our model can predict the evolution of the nonconserved system with good accuracy. However, prediction for the conserved system fails to preserve the conservation of the order parameter. Furthermore, we find that the prediction for the domain coarsening characterized by a single length scale is consistent with the Allen-Cahn growth law for ferromagnetic ordering. In contrast, we observe deviation from the Lifshitz-Slyozov growth law for the phase-separating binary mixture. Beyond the Ising ferromagnet and binary alloys, our model could be applied to the evolution of other nonequilibrium phenomena, such as surface-directed spinoidal decomposition and percolation.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144198351","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}
Akhila Henry, Rajan Sundaravaradhan, Nithin Nagaraj
{"title":"Simplified neurochaos learning architectures for data classification.","authors":"Akhila Henry, Rajan Sundaravaradhan, Nithin Nagaraj","doi":"10.1063/5.0263796","DOIUrl":"https://doi.org/10.1063/5.0263796","url":null,"abstract":"<p><p>Developing machine learning algorithms that can classify datasets with higher accuracy and efficiency is crucial in practical applications. Neurochaos learning (NL) is a recently proposed algorithm that is inspired by the chaotic firing of neurons in the brain. NL has shown promise in recent times both in terms of classification accuracy and in the number of samples needed for training. In this study, we propose a novel simplification of the neurochaos learning algorithm by reducing the number of features needed for classification and also reducing the number of hyperparameters needed to be tuned. By using a single feature of the chaotic neural traces (orbit generated by chaotic map) of NL and by using only one hyperparameter, we demonstrate a significant boost in run time of the algorithm while retaining comparable classification accuracy. This single feature could either be the mean of the chaotic neural traces (Tracemean) or the Fluctuation Index (FI) of the chaotic neural traces. The classifier itself could either be a simple cosine similarity (Tracemean ChaosNet, FI ChaosNet) or any of the classical machine learning (ML) classifiers (Tracemean+ML, FI+ML). We compare the performance of these newly proposed simplified NL algorithms on ten publicly available datasets. The proposed simplified NL architectures in this study are able to efficiently classify datasets while taking much less run time. The fact that only a single hyperparameter needs to be tuned in both architectures (Tracemean ChaosNet and FI ChaosNet) makes them very attractive for practical applications with the ease of interpretability.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144198357","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":"Spatial locking of chimera states to frequency heterogeneity in nonlocally coupled oscillators.","authors":"Petar Mircheski, Hiroya Nakao","doi":"10.1063/5.0266425","DOIUrl":"https://doi.org/10.1063/5.0266425","url":null,"abstract":"<p><p>Chimera states in systems of nonlocally coupled oscillators, i.e., self-organized coexistence of coherent and incoherent oscillator populations, have attracted much attention. In this study, we consider the effect of frequency heterogeneities on the chimera state and reveal that it induces spatial locking of the chimera state, i.e., the coherent and incoherent domains align with lower- and higher-frequency regions, respectively, in a self-adaptive manner. Using an extended self-consistency approach, we show that such spatially locked chimera states can be reproduced as steady solutions of the system in the continuum limit. Furthermore, we develop a variational argument to explain the mechanism leading to spatial locking. Our analysis reveals how heterogeneity can affect the collective dynamics of the chimera states and offers insights into their control and applications.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144198358","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}
Marcus W Beims, Pedro G Lind, Thorsten Pöschel, Támas Tél, Miklós Vincze, Dietrich E Wolf
{"title":"Imre M. Jánosi (1963-2023).","authors":"Marcus W Beims, Pedro G Lind, Thorsten Pöschel, Támas Tél, Miklós Vincze, Dietrich E Wolf","doi":"10.1063/5.0274421","DOIUrl":"https://doi.org/10.1063/5.0274421","url":null,"abstract":"","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144198352","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}