IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0269370

Arvind Kumar Mishra, Lalchand Verma, Omid Nikan, Mahboubeh Molavi-Arabshahi

引用次数: 0

Regularization of a conceptual model for Dansgaard-Oeschger events. Dansgaard-Oeschger事件概念模型的正则化。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0244302

Bryony Hobden, Peter Ashwin, Paul D L Ritchie

{"title":"Regularization of a conceptual model for Dansgaard-Oeschger events.","authors":"Bryony Hobden, Peter Ashwin, Paul D L Ritchie","doi":"10.1063/5.0244302","DOIUrl":"https://doi.org/10.1063/5.0244302","url":null,"abstract":"The Dansgaard-Oeschger events are sudden and irregular warmings of the North Atlantic region that occurred during the last glacial period. A key characteristic of these events is a rapid shift to warmer conditions (interstadial), followed by a slower cooling toward a colder climate (stadial), resulting in a saw-tooth pattern in regional proxy temperature records. These events occurred many times during the last 100 000 years and have been hypothesized to result from various mechanisms, including millennial variability of the ocean circulation and/or nonlinear interactions between ocean circulation and other processes. Our starting point is a non-autonomous, conceptual, but process-based, model of Boers et al. [Proc. Natl. Acad. Sci. 115, E11005-E11014 (2018)] that includes a slowly varying non-autonomous forcing represented by reconstructed global mean temperatures. This model can reproduce Dansgaard-Oeschger events in terms of shape, amplitude, and frequency to a reasonable degree. However, the model of Boers et al. has instantaneous switches between different sea-ice evolution mechanisms on crossing thresholds and, therefore, cannot show early warning signals of the onset or offset of these warming events. In this paper, we regularize this model by adding a fast dynamic variable so that the switching occurs smoothly and in finite time. This means the model has the potential to show early warning signals for sudden changes. However, the additional fast timescale means these early warning signals may have short time horizons. Nonetheless, we find some evidence of early warning for the transition between slow and rapid cooling for the model.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 8","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144793532","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}

引用次数: 0

Quantum particle statistics in classical shallow water waves. 经典浅水波浪中的量子粒子统计。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0263305

Idan Ceausu, Yuval Dagan

引用次数: 0

Phase chimera states: Frozen patterns of disorder. 相嵌合体状态：混乱的冻结模式。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0275286

E R Zajdela, D M Abrams

引用次数: 0

Task-specific node pruning enhances computational efficiency of reservoir computing networks. 针对特定任务的节点修剪提高了库计算网络的计算效率。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0273535

Manish Yadav, Merten Stender

{"title":"Task-specific node pruning enhances computational efficiency of reservoir computing networks.","authors":"Manish Yadav, Merten Stender","doi":"10.1063/5.0273535","DOIUrl":"https://doi.org/10.1063/5.0273535","url":null,"abstract":"The relationship between a reservoir network structure and the overall performance of a reservoir computer remains an unanswered question, particularly when searching for an optimal yet small network. In this study, we introduce a systematic, task-specific node-pruning framework that enhances the efficiency while decreasing the size of the reservoir networks. We demonstrate that large networks can be compressed while preserving-or even improving-performance by node removal. Our findings reveal the emergence of optimal subnetwork structures from larger Erdös-Rényi random networks, indicating that efficiency is governed not merely by size but by topological organization. We observe that the pruning process enhances the reservoir's structural efficiency by forming a self-organized asymmetric distribution of input-receiving and readout nodes, with significant changes in key graph-theoretic measures, such as consistent decreases in spectral radius and average degree. Interestingly, the best-performing pruned networks exhibited significantly lower linear memory capacities over the initial networks, which often did not align with the memory demands of the respective tasks. We show that pruning leads to non-uniform network refinements, where specific nodes and connectivity patterns become critical for information flow and task-specific memory retention. This work offers fundamental insights into how structural optimization influences reservoir dynamics, providing a pathway toward designing more efficient, scalable, and interpretable machine learning architectures.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 8","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144834263","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}

引用次数: 0

Dynamical analysis and solutions of coupled 4D fractional differential systems with applications to predictability limit quantification in ocean-atmosphere models. 耦合四维分数微分系统的动力学分析和解及其在海洋-大气模式可预测性极限量化中的应用。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0283492

Xiaoyu Chen, Hongtao Fan, Yajing Li

{"title":"Dynamical analysis and solutions of coupled 4D fractional differential systems with applications to predictability limit quantification in ocean-atmosphere models.","authors":"Xiaoyu Chen, Hongtao Fan, Yajing Li","doi":"10.1063/5.0283492","DOIUrl":"https://doi.org/10.1063/5.0283492","url":null,"abstract":"For coupled two-dimensional fractional differential systems, a new two-step fractional-order Runge-Kutta method is proposed in this paper, which can reach a convergence order of 2α, with α being the fractional-order number. Further, we extend the two-step fractional-order Runge-Kutta algorithm to any coupled n-dimensional fractional differential system while maintaining convergence and consistency. To demonstrate the validity of the proposed method, numerical experiments are given for a four-dimensional fractional Lorenz system, and the dynamics of the four-dimensional fractional Lorenz system is analyzed using Lyapunov characteristic exponents, bifurcation diagrams, chaos diagrams, and C0 complexity. The results demonstrate that the system exhibits a diverse dynamical behavior and a broader range of fractional orders [0.43, 1] is accessible to the periodic orbit at the same parameter, compared to previous findings [He et al., Math. Methods Appl. Sci. 39, 2965-2973 (2016)]. Finally, we use global attractor radius and attractor radius to investigate the predictability of the coupled fractional-order ocean-atmosphere system [Li et al., Clim. Dyn. 51, 2359-2374 (2018)]. The results show that both global attractor radius and attractor radius decrease with decreasing fractional order, and the smaller the initial perturbation, the longer it takes to reach the attractor radius, but the attractor radius to the global attractor radius is not significantly correlated with the initial perturbation. These findings suggest that the predictability of the coupled fractional ocean-atmosphere system is limited by the presence of long-range memory effects captured in the fractional-order differential equations. By offering quantitative assessments of predictability, these approaches enhance our understanding of the intricate dynamics within such systems and can support informed decision-making in addressing and mitigating the effects of climate change on the global atmosphere and oceans.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 8","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144764641","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}

引用次数: 0

Dynamic analysis of a generalized attention deficit disorder model with Soboleva activation functions. 具有Soboleva激活函数的广义注意缺陷障碍模型的动态分析。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0280557

L Moysis, M Lawnik, K F Kollias, M S Baptista, S Goudos, G Fragulis

引用次数: 0

Recurrence condensation during critical transitions in complex systems. 复杂系统临界跃迁过程中的重复凝聚。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0267157

Manaswini Jella, Induja Pavithran, Vishnu R Unni, Norbert Marwan, Jürgen Kurths, R I Sujith

{"title":"Recurrence condensation during critical transitions in complex systems.","authors":"Manaswini Jella, Induja Pavithran, Vishnu R Unni, Norbert Marwan, Jürgen Kurths, R I Sujith","doi":"10.1063/5.0267157","DOIUrl":"https://doi.org/10.1063/5.0267157","url":null,"abstract":"Critical transitions in complex systems pose challenges for the healthy functioning of natural and engineered systems, sometimes with catastrophic outcomes. These critical points, where small changes cause large regime shifts, are difficult to detect-especially in noisy, high-dimensional settings. We investigate such a transition from chaotic to periodic oscillations via intermittency in a turbulent fluid mechanical system by using recurrence analysis. Recurrence plots (RPs) constructed from the time series of a state variable reveal a distinct progression from disordered, short broken diagonal lines to patches of ordered short diagonal lines and, ultimately, to a pattern of long continuous diagonal lines. This evolution in the recurrence patterns captures a transition from dynamics involving multiple time scales to a dominant single time scale; we term this phenomenon \"recurrence condensation.\" We quantify recurrence condensation using recurrence quantification measures, such as the recurrence time, determinism, entropy, laminarity, and trapping time, all of which show collapse to a single dominant time scale. Furthermore, these recurrence measures exhibit power-law scaling with the deviation of the control parameter from the critical point. Optimizing for the best power law reveals the critical value of the parameter. We apply this method to the synthetic data from a basic noisy Hopf bifurcation model and confirm that the detected critical point coincides with the bifurcation point. Our findings offer insights into identifying the critical points in noisy systems with gradual transitions, where the transition point is not well defined.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 8","pages":""},"PeriodicalIF":3.2,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144764644","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}

引用次数: 0

Two-level atom witness of thermalization of multimode optical fibers. 多模光纤热化的二能级原子见证。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0278293

M Wanic, R Khomeriki, S Stagraczyński, M I Katsnelson, Z Toklikishvili, L Chotorlishvili

引用次数: 0

Chaotic dynamics for the two-body problem on a sphere. 球面上二体问题的混沌动力学。

IF 3.2 2区数学

Chaos Pub Date : 2025-08-01 DOI: 10.1063/5.0285476

Sergey Bolotin

引用次数: 0

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