{"title":"Input signal accumulation capability of the FitzHugh-Nagumo neuron.","authors":"A V Bukh, I A Shepelev, T E Vadivasova","doi":"10.1063/5.0243083","DOIUrl":"https://doi.org/10.1063/5.0243083","url":null,"abstract":"<p><p>We present numerical results on the effects of two presynaptic FitzHugh-Nagumo neurons on a postsynaptic neuron under unidirectional electrical coupling. The presynaptic neurons affect the postsynaptic neuron not simultaneously but with a certain time shift. We consider cases where the amplitudes of the presynaptic spikes can be both higher and lower than the excitation threshold level. The latter case receives the main attention in our work. We carefully examine the conditions under which the postsynaptic neuron is excited by the two asynchronous external spikes. With arbitrarily chosen parameters, the FitzHugh-Nagumo neuron is almost incapable of accumulating the energy of external signals, unlike, for example, the leaky integrate-and-fire neuron. In this case, the postsynaptic neuron only excites with a very short time delay between external impulses. However, we have discovered, for the first time, a parameter region where neuron excitation is possible even with significant time delays between presynaptic impulses with subthreshold amplitudes. We explain this effect in detail and describe the mechanism behind its occurrence. We identify the boundaries of this region in the parameter plane of time delay and coupling coefficient by varying the control parameter values of the neurons. The FitzHugh-Nagumo neuron has not previously been used as a node in spiking neural networks for training via spike-timing-dependent plasticity due to the lack of an integrate-and-fire effect. However, the detection of a certain range of parameters makes the potential application of this neuron for STDP training possible.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142766832","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}
Fanrui Wang, Zhouchao Wei, Wei Zhang, Tomasz Kapitaniak
{"title":"Hopf-like bifurcations and multistability in a class of 3D Filippov systems with generalized Liénard's form.","authors":"Fanrui Wang, Zhouchao Wei, Wei Zhang, Tomasz Kapitaniak","doi":"10.1063/5.0231485","DOIUrl":"https://doi.org/10.1063/5.0231485","url":null,"abstract":"<p><p>Based on the observable conditions of control systems, a class of 3D Filippov systems with generalized Liénard's form is proposed. The bifurcation conditions for two types of Hopf-like bifurcations are investigated by considering the stability changes of the sliding region and the invisible two-fold point. The primary objective of this paper is to elucidate the sudden transitions between attractors. Phase portraits, bifurcation diagrams, time series diagrams, Poincaré maps, and basins of attraction are utilized to illustrate the novel and intriguing chaotic behaviors. The simulation results indicate that after undergoing the Hopf-like bifurcation of type I, the proposed system can exhibit multiple types of attractors within remarkably narrow intervals. Even when the pseudo-equilibrium disappears, the multistable phenomena can still emerge by adjusting the parameters.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142784308","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":"A novel analytical tool for complex propagation processes in networks: High-order dynamic equation.","authors":"Jiahui Song, Zaiwu Gong","doi":"10.1063/5.0223566","DOIUrl":"https://doi.org/10.1063/5.0223566","url":null,"abstract":"<p><p>Controlling the spread of epidemics in complex networks has always been an important research problem in the field of network science and has been widely studied by many scholars so far. One of the key problems in the transmission process of epidemics in complex networks is the transmission mechanism. At present, the transmission mechanism in complex networks can be divided into simple transmission and complex transmission. Simple transmission has been widely studied and the theory is relatively mature, while complex transmission still has many questions to answer. In fact, in the complex transmission process, the higher-order structure of the network plays a very important role, which can affect the transmission speed, final scale, and transmission path of the epidemic by strengthening the mechanism. However, due to the lack of complex dynamic analysis tools, the measurement of influence on propagation is still at the low-dimensional node level. Therefore, in this paper, we propose a set of closed dynamic higher-order structure equations to gain insight into the complex propagation process in the network, which breaks the inherent thinking and enables us to reexamine the complex dynamic behavior more clearly from the higher-order level rather than just from the node level, opening up a new way to analyze the higher-order interaction on the dynamic network. We apply the proposed high-order dynamic equations to a complex susceptible-infection-recovery epidemiological model on two real and synthetic networks, and extensive numerical simulation results demonstrate the effectiveness of the proposed approach. Our research results help to deepen the understanding of the relationship between complex propagation mechanisms and higher-order structures and develop a complete set of complex dynamic analysis tools that can be extended to higher-order forms to help in-depth understanding of the propagation rules and mechanisms in complex propagation processes, providing an important theoretical basis for predicting, analyzing, and controlling complex propagation processes.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821971","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":"Enhanced long short-term memory architectures for chaotic systems modeling: An extensive study on the Lorenz system.","authors":"Roland Bolboacă, Piroska Haller","doi":"10.1063/5.0238619","DOIUrl":"https://doi.org/10.1063/5.0238619","url":null,"abstract":"<p><p>Despite recent advancements in machine learning algorithms, well-established models like the Long Short-Term Memory (LSTM) are still widely used for modeling tasks. This paper introduces an enhanced LSTM variant and explores its capabilities in multiple input single output chaotic system modeling, offering a large-scale analysis that focuses on LSTM gate-level architecture, the effects of noise, non-stationary and dynamic behavior modeling, system parameter drifts, and short- and long-term forecasting. The experimental evaluation is performed on datasets generated using MATLAB, where the Lorenz and Rössler system equations are implemented and simulated in various scenarios. The extended analysis reveals that a simplified, less complex LSTM-based architecture can be successfully employed for accurate chaotic system modeling without the need for complex deep learning methodologies. This new proposed model includes only three of the four standard LSTM gates, with other feedback modifications.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142845801","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}
Bo Gao, Pengfei Zuo, Xiangfeng Dai, Rongrong Fu, Zhiyan Bai, Zhongzhou Lan
{"title":"Cooperation resonance based on link strategy reinforcement learning and conformity.","authors":"Bo Gao, Pengfei Zuo, Xiangfeng Dai, Rongrong Fu, Zhiyan Bai, Zhongzhou Lan","doi":"10.1063/5.0239335","DOIUrl":"https://doi.org/10.1063/5.0239335","url":null,"abstract":"<p><p>We propose a game model that integrates reinforcement learning (RL) with link strategies and conformity behavior to investigate the emergence and maintenance of cooperation. The model operates on a lattice network with periodic boundaries and includes two types of nodes: RL nodes with link strategies and conformist nodes. Simulation results reveal a range of critical mass. Within this range, the interaction between these two types of nodes exhibits a nonlinear response between the cooperation rate and the temptation to betray, resulting in the phenomena of resonance-like cooperation and resonance-like defection, showing a nonlinear response between the cooperation rate and the temptation to betray. This study reveals the complex interactions between the two strategies as well as their influence on system behavior through numerical simulations and analysis. Our results provide fresh insights into understanding and promoting cooperative behavior between artificial intelligence and humans.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142766734","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}
Suoxia Miao, Ruxin Xiong, Qing An, Cuihong Bao, Yaping Sun, Housheng Su
{"title":"Distributed optimization consensus for multi-agent systems on matrix-weighted networks.","authors":"Suoxia Miao, Ruxin Xiong, Qing An, Cuihong Bao, Yaping Sun, Housheng Su","doi":"10.1063/5.0235296","DOIUrl":"https://doi.org/10.1063/5.0235296","url":null,"abstract":"<p><p>In this paper, the distributed optimization consensus issues for both first-order continuous time (CT) and discrete-time (DT) multi-agent systems (MASs) on matrix-weighted networks are studied. In order to make each agent achieve optimization consensus, a new matrix-weighted distributed optimization algorithm for CT and DT MASs is proposed. Using the Lyapunov stability theory and matrix theory, the optimization consensus conditions are obtained, respectively. Finally, the correctness of our results is verifiied by numerical examples.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142766736","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":"Tuning domain wall dynamics in a notched ferromagnetic nanostrip with Rashba effect.","authors":"Sarabindu Dolui, Sharad Dwivedi","doi":"10.1063/5.0231491","DOIUrl":"https://doi.org/10.1063/5.0231491","url":null,"abstract":"<p><p>This work delineates a comprehensive investigation of the static and kinetic depinning of a domain wall in a notched ferromagnetic nanostrip. More precisely, we consider a 180° Bloch-type domain wall and examine its behavior under the action of an applied magnetic field, spin-polarized electric current, and Rashba field. Moreover, we assume an artificial notch positioned at the edges of the nanostrip, serving as a pinning site for the wall. We characterize domain walls' pinning and depinning dynamics in the steady-state regime by using the classical Schryer and Walker trial-function approach. The results demonstrate that the static depinning limits of external stimuli are more significant than the kinetic depinning. It is also observed that higher Rashba field strength increases the static depinning fields/currents while decreasing kinetic depinning ones. Furthermore, both static and kinetic depinning thresholds are elevated with higher damping, whereas an increase in the non-adiabatic spin-transfer parameter leads to a reduction. Finally, we present numerical illustrations of the analytical results, showing good qualitative agreement with the literature.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142766276","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":"Unsupervised data-driven response regime exploration and identification for dynamical systems.","authors":"Maor Farid","doi":"10.1063/5.0173938","DOIUrl":"https://doi.org/10.1063/5.0173938","url":null,"abstract":"<p><p>Data-Driven Response Regime Exploration and Identification (DR2EI) is a novel and fully data-driven method for identifying and classifying response regimes of a dynamical system without requiring human intervention. This approach is a valuable tool for exploring and discovering response regimes in complex dynamical systems, especially when the governing equations and the number of distinct response regimes are unknown, and the system is expensive to sample. Additionally, the method is useful for order reduction, as it can be used to identify the most dominant response regimes of a given dynamical system. DR2EI utilizes unsupervised learning algorithms to transform the system's response into an embedding space that facilitates regime classification. An active sequential sampling approach based on Gaussian Process Regression is used to efficiently sample the parameter space, quantify uncertainty, and provide optimal trade-offs between exploration and exploitation. The performance of the DR2EI method was evaluated by analyzing three established dynamical systems: the mathematical pendulum, the Lorenz system, and the Duffing oscillator, and its robustness to noise was validated across a range of noise magnitudes. The method was shown to effectively identify a variety of response regimes with both similar and distinct topological features and frequency content, demonstrating its versatility in capturing a wide range of behaviors. While it may not be possible to guarantee that all possible regimes will be identified, the method provides an automated and efficient means for exploring the parameter space of a dynamical system and identifying its underlying \"sufficiently dominant\" response regimes without prior knowledge of the system's equations or behavior.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142766359","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":"Evolutionary dynamics in spatial public goods games with environmental feedbacks.","authors":"Rui Ding, Xianjia Wang, Jinhua Zhao, Cuiling Gu, Wenman Chen","doi":"10.1063/5.0242366","DOIUrl":"https://doi.org/10.1063/5.0242366","url":null,"abstract":"<p><p>Collective actions aimed at achieving goals such as resource sustainability and environmental protection often face conflicting interests between individuals and groups. These social dilemmas can be modeled using public goods games and collective risk dilemmas. However, in reality, multiple generations share a common pool of resources, leading to high costs for today's overexploitation that impacts future generations' welfare. This delayed effect creates a multigenerational conflict. To address this, we develop a coupled social-ecological coevolutionary model by establishing a relationship between individual payoffs and regional environmental quality. Our goal is to study how cooperative behaviors spread in a public goods game with environmental feedback and to identify the factors influencing this spread. We achieve this by examining the mechanisms behind certain phases and phase transitions, monitoring the spatial distribution of strategies, and assessing the environmental quality of all regions. Our findings reveal some counterintuitive results. For instance, despite cooperators' ability to enhance the environment, the overall level of cooperation in the system sometimes decreases. This is linked to cooperative clusters being invaded by defectors within the clusters' cracks. Additionally, the destructive power of defection and the cost of cooperation have more complex effects on the system.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142799578","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":"Skeletal structure in domain of periodicity of the forced Brusselator.","authors":"Dariel M Maranhão, Rene O Medrano-T","doi":"10.1063/5.0238883","DOIUrl":"https://doi.org/10.1063/5.0238883","url":null,"abstract":"<p><p>We report the peculiar organization of oscillations in the forced Brusselator system, found in the parameter space as a nested structure of regular and chaotic phases. To this end, we apply the winding number concept, conceived for nonlinear driven oscillators, to expose all oscillatory phases in the nested structure. First, we use the period and torsion of orbits to describe every periodic oscillation in the parameter spaces, describing the nested structure in high-resolution phase diagrams. Next, we propose a basic structure organizing the periodicity, a \"skeletal set\" whose properties elucidate the genealogy and composition of oscillations in the nested structure. Finally, we discuss the application of the skeletal structure in a diversity of Brusselator's oscillatory regimes.</p>","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"34 12","pages":""},"PeriodicalIF":2.7,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821979","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}