IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0237050

B Hartmann, G Ódor, K Benedek, I Papp

{"title":"Studying power-grid synchronization with incremental refinement of model heterogeneity.","authors":"B Hartmann, G Ódor, K Benedek, I Papp","doi":"10.1063/5.0237050","DOIUrl":"https://doi.org/10.1063/5.0237050","url":null,"abstract":"The dynamics of electric power systems are widely studied through the phase synchronization of oscillators, typically with the use of the Kuramoto equation. While there are numerous well-known order parameters to characterize these dynamics, shortcoming of these metrics are also recognized. To capture all transitions from phase disordered states over phase locking to fully synchronized systems, new metrics were proposed and demonstrated on homogeneous models. In this paper, we aim to address a gap in the literature, namely, to examine how the gradual improvement of power grid models affects the goodness of certain metrics. To study how the details of models are perceived by the different metrics, 12 variations of a power grid model were created, introducing varying levels of heterogeneity through the coupling strength, the nodal powers, and the moment of inertia. The grid models were compared using a second-order Kuramoto equation and adaptive Runge-Kutta solver, measuring the values of the phase, the frequency, and the universal order parameters. Finally, frequency results of the models were compared to grid measurements. We found that the universal order parameter was able to capture more details of the grid models, especially in cases of decreasing moment of inertia. Even the most heterogeneous models showed notable synchronization, encouraging the use of such models. Finally, we show local frequency results related to the multi-peaks of static models, which implies that spatial heterogeneity can also induce such multi-peak behavior.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143001083","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

Reliable detection of directional couplings using cross-vector measures. 使用交叉矢量测量可靠地检测方向耦合。

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0238375

Martin Brešar, Ralph G Andrzejak, Pavle Boškoski

{"title":"Reliable detection of directional couplings using cross-vector measures.","authors":"Martin Brešar, Ralph G Andrzejak, Pavle Boškoski","doi":"10.1063/5.0238375","DOIUrl":"https://doi.org/10.1063/5.0238375","url":null,"abstract":"Detecting directional couplings from time series is crucial in understanding complex dynamical systems. Various approaches based on reconstructed state-spaces have been developed for this purpose, including a cross-distance vector measure, which we introduced in our recent work. Here, we devise two new cross-vector measures that utilize ranks and time series estimates instead of distances. We analyze various deterministic and stochastic dynamics to compare our cross-vector approach against some established state-space-based approaches. We demonstrate that all three cross-vector measures can identify the correct coupling direction for a broader range of couplings for all considered dynamics. Among the three cross-vector measures, the rank-based variant performs the best. Comparing this novel measure to an established rank-based measure confirms that it is more noise-robust and less affected by linear cross-correlation. To extend this comparison to real-world signals, we combine both measures with the method of surrogates and analyze a database of electroencephalographic (EEG) recordings from epilepsy patients. This database contains signals from brain areas where the patients' seizures were detected first and signals from brain areas that were not involved in the seizure onset. A better discrimination between these signal classes is obtained by the cross-rank vector measure. Additionally, this measure proves to be robust to non-stationarity, as its results remain nearly unchanged when the analysis is repeated for the subset of EEG signals that were identified as stationary in previous work. These findings suggest that the cross-vector approach can serve as a valuable tool for researchers analyzing complex time series and for clinical applications.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142962121","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

Characterization of dynamic features in the walking videos of patients with adolescent idiopathic scoliosis based on moving entropy. 基于运动熵的青少年特发性脊柱侧凸患者行走视频的动态特征表征。

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0238864

Jiong Zhang, Yuhao Han, Xiangjie Yin, Liang Wang, Xueyi Zhang, Keqiang Dong

{"title":"Characterization of dynamic features in the walking videos of patients with adolescent idiopathic scoliosis based on moving entropy.","authors":"Jiong Zhang, Yuhao Han, Xiangjie Yin, Liang Wang, Xueyi Zhang, Keqiang Dong","doi":"10.1063/5.0238864","DOIUrl":"https://doi.org/10.1063/5.0238864","url":null,"abstract":"Adolescent idiopathic scoliosis (AIS), which typically occurs in patients between the ages of 10 and 18, can be caused by a variety of reasons, and no definitive cause has been found. Early diagnosis of AIS or timely recognition of progression is crucial for the prevention of spinal deformity and the reduction of the risk of surgery or postponement. However, it remains a significant challenge. The purpose of this study is to develop an easy-to-use, non-invasive, and portable method for early diagnosis of AIS. A new framework of moving entropy-based computer vision method is presented, which can determine the severity of AIS by analyzing patients' walking videos. First, Alphapose system and direct linear transformation method are employed to estimate 3D keypoint coordinates. Then, the joint angle-based and joint distance-based dynamic network are constructed. Based on these works, the new measures called moving angle entropy and moving edge-weighted graph entropy are proposed and fused using canonical correlation analysis. Finally, the power spectral exponents of entropy sequences are calculated and used in recognizing the severity of AIS. A comparison with healthy subjects and statistical analysis for entropy values can provide effective information for quantifying AIS. The recognized results of our proposed method were also comparable with the clinical diagnosis of Cobb angle from imaging by a certified clinician.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143000860","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

An "opinion reproduction number" for infodemics in a bounded-confidence content-spreading process on networks.

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0206431

Heather Z Brooks, Mason A Porter

{"title":"An \"opinion reproduction number\" for infodemics in a bounded-confidence content-spreading process on networks.","authors":"Heather Z Brooks, Mason A Porter","doi":"10.1063/5.0206431","DOIUrl":"https://doi.org/10.1063/5.0206431","url":null,"abstract":"We study the spreading dynamics of content on networks. To do this, we use a model in which content spreads through a bounded-confidence mechanism. In a bounded-confidence model (BCM) of opinion dynamics, the agents of a network have continuous-valued opinions, which they adjust when they interact with agents whose opinions are sufficiently close to theirs. Our content-spreading model, which one can also interpret as an independent-cascade model, introduces a twist into BCMs by using bounded confidence for the content spread itself. We define an analog of the basic reproduction number from disease dynamics that we call an opinion reproduction number. A critical value of the opinion reproduction number indicates whether or not there is an \"infodemic\" (i.e., a large content-spreading cascade) of content that reflects a particular opinion. By determining this critical value, one can determine whether or not an opinion dies off or propagates widely as a cascade in a population of agents. Using configuration-model networks, we quantify the size and shape of content dissemination by calculating a variety of summary statistics, and we illustrate how network structure and spreading-model parameters affect these statistics. We find that content spreads most widely when agents have a large expected mean degree or a large receptiveness to content. When the spreading process slightly exceeds the infodemic threshold, there can be longer dissemination trees than for larger expected mean degrees or receptiveness (which both promote content sharing and hence help push content spread past the infodemic threshold), even though the total number of content shares is smaller.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143063905","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

Analysis of a class of two-delay fractional differential equation.

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0240447

Sachin Bhalekar, Pragati Dutta

引用次数: 0

How a responsive reproduction factor is determinant in a prey-predator dynamics: A numerical and analytical study in a discrete-time model.

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0239007

M S Bittencourt, E L Brugnago, Z O Guimarães-Filho, I L Caldas, A S Reis

引用次数: 0

From homophily to exclusion in small social systems. 从同质到排斥在小的社会系统。

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0243490

Malgorzata J Krawczyk, Krzysztof Kułakowski

引用次数: 0

Transient chaos and periodic structures in a model of neuronal early afterdepolarization. 神经元早期后去极化模型中的瞬态混沌和周期结构。

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0239031

Rafael V Stenzinger, M H R Tragtenberg

{"title":"Transient chaos and periodic structures in a model of neuronal early afterdepolarization.","authors":"Rafael V Stenzinger, M H R Tragtenberg","doi":"10.1063/5.0239031","DOIUrl":"https://doi.org/10.1063/5.0239031","url":null,"abstract":"The presence of chaos is ubiquitous in mathematical models of neuroscience. In experimental neural systems, chaos was convincingly demonstrated in membranes, neurons, and small networks. However, its effects on the brain have long been debated. In this work, we use a three-dimensional map-based membrane potential model, the logistic KTz, to study chaos in single and coupled neurons. We first obtain an alternative phase diagram for the model using the interspike interval (ISI), evidencing a region of slow spikes (SS), missing from the original diagram of the KTz model. A large chaotic region is found inside the SS phase. Embedded in chaos are several self-similar periodic structures, such as shrimp-shaped domains and other structures. Sampling the behavior of neurons in this diagram, we detect a novel type of action potential, the neuronal early afterdepolarization (nEAD). EADs are pathological oscillations during the action potential, commonly found in cardiac cells and believed to be chaotic and responsible for generating arrhythmias in the heart. nEAD was found experimentally in neurons in a type of epilepsy. We study two chemically coupled neurons with this behavior. We identify and characterize transient chaos in their interaction. A phase diagram for this system presents a novel type of self-similar periodic structures, where the structures appear \"chopped\" in pieces.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142976824","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

Point process analysis of geographical diffusion of news in Argentina. 阿根廷新闻地理传播的点过程分析。

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0240799

L L García, G Tirabassi, C Masoller, P Balenzuela

{"title":"Point process analysis of geographical diffusion of news in Argentina.","authors":"L L García, G Tirabassi, C Masoller, P Balenzuela","doi":"10.1063/5.0240799","DOIUrl":"https://doi.org/10.1063/5.0240799","url":null,"abstract":"The diffusion of information plays a crucial role in a society, affecting its economy and the well-being of the population. Characterizing the diffusion process is challenging because it is highly non-stationary and varies with the media type. To understand the spreading of newspaper news in Argentina, we collected data from more than 27 000 articles published in six main provinces during 4 months. We classified the articles into 20 thematic axes and obtained a set of time series that capture daily newspaper attention on different topics in different provinces. To analyze the data, we use a point process approach. For each topic, n, and for all pairs of provinces, i and j, we use two measures to quantify the synchronicity of the events, Qs(i,j), which quantifies the number of events that occur almost simultaneously in i and j, and Qa(i,j), which quantifies the direction of news spreading. Our analysis unveils how fast the information diffusion process is, showing pairs of provinces with very similar and almost simultaneous temporal variations of media attention. On the other hand, we also calculate other measures computed from the raw time series, such as Granger Causality and Transfer Entropy, which do not perform well in this context because they often return opposite directions of information transfer. We interpret this as due to the characteristics of the data, which is highly non-stationary, and of the information diffusion process, which is very fast and probably acts at a sub-resolution time scale.","PeriodicalId":9974,"journal":{"name":"Chaos","volume":"35 1","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142982809","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

Evolution modeling and control of networked dynamic games with event-triggering mechanism. 具有事件触发机制的网络动态博弈演化建模与控制。

IF 2.7 2区数学

Chaos Pub Date : 2025-01-01 DOI: 10.1063/5.0235716

Xiangyong Chen, Jun-E Feng, Wenying Xu, Jinde Cao, Jianlong Qiu

引用次数: 0

Chaos最新文献