Nonlinear Dynamics

非线性动力学
  • 文章类型: Journal Article
    在系统和合成生物学中,建立新兴生物学特性与网络结构存储库之间的映射关系很大。适应是一种至关重要的生物学特性,可以在环境干扰的情况下促进调节。本文提出了一种非线性系统理论驱动的框架,以确定针对任意大小的外部干扰进行完美适应的设计原则。根据有关网络的先验信息,我们使用非线性系统理论为适应构建了精确的数学条件。我们首先推导出完美适应恒定输入干扰的数学条件。随后,我们将这些条件转化为小型网络中适应的特定必要结构要求,然后扩展到认为,对于任何规模的网络,只有两类体系结构可以在整个状态空间中提供本地适应,即,非相干前馈(IFF)结构和带缓冲节点的负反馈环路(NFB)。额外的积极性约束进一步缩小了可接受的网络结构集。这也有助于在给定恒定输入扰动的情况下建立稳态的全局渐近稳定性。所提出的方法没有假设任何关于潜在速率动力学的明确知识,除了一些最小的假设。最后,我们还讨论了某些IFF网络在存在下游连接的情况下提供自适应的不可行性。此外,我们提出了一种基于非线性系统理论的通用和新颖的算法,以揭示全局适应的设计原则。详细而广泛的模拟研究证实了理论发现。
    Establishing a mapping between the emergent biological properties and the repository of network structures has been of great relevance in systems and synthetic biology. Adaptation is one such biological property of paramount importance that promotes regulation in the presence of environmental disturbances. This paper presents a nonlinear systems theory-driven framework to identify the design principles for perfect adaptation with respect to external disturbances of arbitrary magnitude. Based on the prior information about the network, we frame precise mathematical conditions for adaptation using nonlinear systems theory. We first deduce the mathematical conditions for perfect adaptation for constant input disturbances. Subsequently, we translate these conditions to specific necessary structural requirements for adaptation in networks of small size and then extend to argue that there exist only two classes of architectures for a network of any size that can provide local adaptation in the entire state space, namely, incoherent feed-forward (IFF) structure and negative feedback loop with buffer node (NFB). The additional positiveness constraints further narrow the admissible set of network structures. This also aids in establishing the global asymptotic stability for the steady state given a constant input disturbance. The proposed method does not assume any explicit knowledge of the underlying rate kinetics, barring some minimal assumptions. Finally, we also discuss the infeasibility of certain IFF networks in providing adaptation in the presence of downstream connections. Moreover, we propose a generic and novel algorithm based on non-linear systems theory to unravel the design principles for global adaptation. Detailed and extensive simulation studies corroborate the theoretical findings.
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  • 文章类型: Journal Article
    改进的Benjamin-Bona-Mahony(mBBM)模型用于视错觉领域,以描述视觉错觉期间长波在非线性色散介质中的传播(Khater2021)。本文通过利用有理[公式:参见正文]-展开技术来研究mBBM方程,以得出新的解析波解。我们获得的解析解包括双曲,三角,和合理的功能。在特定情况下,这些精确解决方案中的一些与先前发布的结果密切相关,确认我们其他解决方案的有效性。为了提供对不同波传播特性的见解,我们使用2D对这些解决方案进行了深入分析,3D,和密度图。我们还研究了各种参数对模型获得的波解特性的影响。此外,我们采用线性稳定性技术对所考虑的模型进行稳定性分析。此外,我们通过应用相平面理论探讨了相关动力系统的稳定性。这项研究还证明了有理[公式:参见正文]-展开方法在从非线性偏微分方程中分析和提取孤子解方面的功效和能力。
    The modified Benjamin-Bona-Mahony (mBBM) model is utilized in the optical illusion field to describe the propagation of long waves in a nonlinear dispersive medium during a visual illusion (Khater 2021). This article investigates the mBBM equation through the utilization of the rational [Formula: see text]-expansion technique to derive new analytical wave solutions. The analytical solutions we have obtained comprise hyperbolic, trigonometric, and rational functions. Some of these exact solutions closely align with previously published results in specific cases, affirming the validity of our other solutions. To provide insights into diverse wave propagation characteristics, we have conducted an in-depth analysis of these solutions using 2D, 3D, and density plots. We also investigated the effects of various parameters on the characteristics of the obtained wave solutions of the model. Moreover, we employed the techniques of linear stability to perform stability analysis of the considered model. Additionally, we have explored the stability of the associated dynamical system through the application of phase plane theory. This study also demonstrates the efficacy and capabilities of the rational [Formula: see text]-expansion approach in analyzing and extracting soliton solutions from nonlinear partial differential equations.
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  • 文章类型: Journal Article
    本研究手稿旨在研究非奇异分数阶导数意义上的新型隐式微分方程,即Atangana-Baleanu-Caputo([公式:参见文本])属于区间(2,3]的任意阶,相对于另一个正函数和递增函数。利用Banach定理和拓扑度定理研究了存在性和唯一性的主要结果。通过采用非线性分析的主题来分析Ulam-Hyers([公式:见正文])类型的稳定性。最后,用一些特殊情况构建和增强了两个示例,以及用于检查主要结果影响的说明性图形。
    This research manuscript aims to study a novel implicit differential equation in the non-singular fractional derivatives sense, namely Atangana-Baleanu-Caputo ([Formula: see text]) of arbitrary orders belonging to the interval (2, 3] with respect to another positive and increasing function. The major results of the existence and uniqueness are investigated by utilizing the Banach and topology degree theorems. The stability of the Ulam-Hyers ([Formula: see text]) type is analyzed by employing the topics of nonlinear analysis. Finally, two examples are constructed and enhanced with some special cases as well as illustrative graphics for checking the influence of major outcomes.
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  • 文章类型: Journal Article
    先前的研究已经证实,甘油三酯葡萄糖(TyG)指数,被认为是胰岛素抵抗的可靠标志,是糖尿病肾病(DKD)的重要风险身分。然而,目前尚不清楚DKD风险是否随着TyG指数的升高而持续线性增加.本研究旨在深入研究TyG指数与2型糖尿病(T2D)DKD风险之间的内在关系。
    这项横断面研究纳入了中国933例T2D患者,将其分为DKD和非DKD组,并按TyG指数水平分层。Logistic回归分析确定了DKD的独立危险因素。使用受限三次样条(RCS)曲线分析评估DKD风险与TyG指数之间的关联。R包“CatPredi”用于确定DKD风险与TyG指数之间关系的最佳临界点,其次是阈值效应分析。
    DKD的患病率为33.01%。在调整混杂因素后,TyG指数被确定为DKD的突出临床危险因素,显示最高的赔率比(OR1.57(1.26-1.94),P<0.001)。RCS分析显示,TyG指数与DKD风险之间存在阈值区间效应的非线性关系。当TyG指数≤9.35时,DKD风险稳定在较低水平;然而,当TyG指数>9.35时,随着TyG指数的升高,DKD风险逐渐增加。在TyG指数>9.35的患者中,每增加1个单位与DKD风险增加1.94倍相关(OR=1.94(1.10-3.43),P=0.022)。
    随着TyG指数的增加,DKD风险呈现阈值效应,最初稳定在低水平,然后在TyG指数高于9.35时逐渐上升。
    UNASSIGNED: Previous studies have confirmed that the triglyceride glucose (TyG) index, recognized as a reliable marker of insulin resistance, is an important risk factor for diabetic kidney disease (DKD). However, it is still unclear whether the DKD risk continues to increase linearly with the elevation of TyG index. This study aimed to thoroughly investigated the intrinsic relationship between TyG index and DKD risk in type 2 diabetes (T2D).
    UNASSIGNED: This cross-sectional study included 933 patients with T2D in China, who were categorized into DKD and non-DKD groups and stratified by TyG index levels. Logistic regression analysis identified the independent risk factors for DKD. The association between DKD risk and TyG index was evaluated using the restricted cubic spline (RCS) curves analysis. The R package \'CatPredi\' was utilized to determine the optimal cut-off point for the relationship between DKD risk and TyG index, followed by threshold effect analysis.
    UNASSIGNED: The prevalence of DKD was 33.01%. After adjusting for confounding factors, TyG index was identified as a prominent clinical risk factor for DKD, showing the highest odds ratio (OR 1.57 (1.26 - 1.94), P<0.001). RCS analysis revealed a non-linear relationship with a threshold interval effect between the TyG index and DKD risk. When TyG index ≤ 9.35, DKD risk plateaued at a low level; however, when TyG index > 9.35, DKD risk increased gradually with rising TyG index. Among patients with TyG index > 9.35, each 1-unit increase was associated with a 1.94-fold increased DKD risk (OR=1.94 (1.10 - 3.43), P=0.022).
    UNASSIGNED: The DKD risk presented a threshold effect with the increase of TyG index, initially stable at a low level, and then gradually rising when the TyG index is above 9.35.
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  • 文章类型: Journal Article
    由于其光学和机械模式之间的辐射-压力耦合,腔光学力学为观察许多有趣的经典和量子非线性现象提供了强大的平台。特别是,由于光机械非线性引起的混沌在基础物理学和从秘密信息处理到光通信的潜在应用中的重要性,因此受到了极大的关注。本文的重点是光机械系统中的混沌动力学。介绍了一般非线性动力学的基本理论和混沌的基本性质。演示了光机械系统中的几种非线性动力学效应。此外,解决了最近在操纵光机械混沌运动方面的显着理论和实验工作。还讨论了混合系统中混沌的未来前景。
    Cavity optomechanics provides a powerful platform for observing many interesting classical and quantum nonlinear phenomena due to the radiation-pressure coupling between its optical and mechanical modes. In particular, the chaos induced by optomechanical nonlinearity has been of great concern because of its importance both in fundamental physics and potential applications ranging from secret information processing to optical communications. This review focuses on the chaotic dynamics in optomechanical systems. The basic theory of general nonlinear dynamics and the fundamental properties of chaos are introduced. Several nonlinear dynamical effects in optomechanical systems are demonstrated. Moreover, recent remarkable theoretical and experimental efforts in manipulating optomechanical chaotic motions are addressed. Future perspectives of chaos in hybrid systems are also discussed.
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  • 文章类型: Journal Article
    现有的端到端语音识别方法通常采用基于CTC和Transformer的混合解码器。然而,这些混合解码器中的误差累积问题阻碍了精度的进一步提高。此外,大多数现有模型都建立在Transformer架构上,这往往是复杂和不友好的小数据集。因此,提出了一种用于语音识别的非线性正则化解码方法。首先,我们介绍了非线性变换器解码器,打破传统的从左到右或从右到左的解码顺序,并实现任何字符之间的关联,减轻小数据集上Transformer体系结构的限制。其次,我们提出了一种新颖的正则化注意力模块来优化注意力得分矩阵,减少早期错误对后期输出的影响。最后,我们引入微小模型来解决模型参数过大的挑战。实验结果表明,我们的模型表现出良好的性能。与基线相比,我们的模型实现了0.12%的识别改进,0.54%,0.51%,和1.2%的Aishell1,Primewords,免费ST中文语料库,和维吾尔语的普通语音16.1数据集,分别。
    Existing end-to-end speech recognition methods typically employ hybrid decoders based on CTC and Transformer. However, the issue of error accumulation in these hybrid decoders hinders further improvements in accuracy. Additionally, most existing models are built upon Transformer architecture, which tends to be complex and unfriendly to small datasets. Hence, we propose a Nonlinear Regularization Decoding Method for Speech Recognition. Firstly, we introduce the nonlinear Transformer decoder, breaking away from traditional left-to-right or right-to-left decoding orders and enabling associations between any characters, mitigating the limitations of Transformer architectures on small datasets. Secondly, we propose a novel regularization attention module to optimize the attention score matrix, reducing the impact of early errors on later outputs. Finally, we introduce the tiny model to address the challenge of overly large model parameters. The experimental results indicate that our model demonstrates good performance. Compared to the baseline, our model achieves recognition improvements of 0.12%, 0.54%, 0.51%, and 1.2% on the Aishell1, Primewords, Free ST Chinese Corpus, and Common Voice 16.1 datasets of Uyghur, respectively.
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  • 文章类型: Journal Article
    本文研究了包含Allee效应的三养食物链模型的动力学,性生殖通才顶级掠食者,以及HollingIV型和Beddington-DeAngelis对不同营养级相互作用的功能响应。分析,我们探索可行的均衡,当地的稳定,和各种分叉,包括Hopf,鞍形节点,超临界,和Bogdanov-Takens分叉.数值结果表明,猎物生长中更高的Allee强度导致物种无法共存,导致物种密度下降。同样,顶级捕食者之间较低的繁殖率和较高的种内竞争强度也阻止了物种的共存。相反,繁殖率的迅速提高和顶级捕食者之间种内竞争强度的降低会增加猎物和顶级捕食者的密度,同时降低中等捕食者的密度。我们还揭示了系统中双稳态和三稳态现象的存在。此外,我们通过引入季节性扰动参数将我们的自治模型扩展到其非自治对应物。非自治模型的数值分析表明,繁殖率和顶级捕食者种内竞争的较高季节强度会引起混沌行为,最大Lyapunov指数也证实了这一点。此外,我们观察到季节性可能导致物种从生态系统中灭绝。诸如Allee效应和猎物的生长速率之类的因素会导致种群密度的周期性。了解这些趋势对于控制生态系统内人口密度的变化至关重要。生态学家,环保主义者,政策制定者将从这项研究中获得的宝贵见解中受益匪浅。具体来说,我们的研究结果为制定旨在在不断变化的环境条件下保护生物多样性和维持生态稳定的未来战略提供了关键指导。通过对现有知识体系的贡献,我们的研究推进了生态科学领域,增强对不同生态条件下捕食者-猎物动态的理解。
    This paper investigates the dynamics of a tritrophic food chain model incorporating an Allee effect, sexually reproductive generalist top predators, and Holling type IV and Beddington-DeAngelis functional responses for interactions across different trophic levels. Analytically, we explore the feasible equilibria, their local stability, and various bifurcations, including Hopf, saddle-node, transcritical, and Bogdanov-Takens bifurcations. Numerical findings suggest that higher Allee intensity in prey growth leads to the inability of species coexistence, resulting in a decline in species density. Likewise, a lower reproduction rate and a higher strength of intraspecific competition among top predators also prevent the coexistence of species. Conversely, a rapid increase in the reproduction rate and a decrease in the strength of intraspecific competition among top predators enhance the densities of prey and top predators while decreasing intermediate predator density. We also reveal the presence of bistability and tristability phenomena within the system. Furthermore, we extend our autonomous model to its nonautonomous counterpart by introducing seasonally perturbed parameters. Numerical analysis of the nonautonomous model reveals that higher seasonal strength in the reproduction rate and intraspecific competition of top predators induce chaotic behavior, which is also confirmed by the maximum Lyapunov exponent. Additionally, we observe that seasonality may lead to the extinction of species from the ecosystem. Factors such as the Allee effect and growth rate of prey can cause periodicity in population densities. Understanding these trends is critical for controlling changes in population density within the ecosystem. Ecologists, environmentalists, and policymakers stand to benefit significantly from the invaluable insights garnered from this study. Specifically, our findings offer pivotal guidance for shaping future strategies aimed at safeguarding biodiversity and maintaining ecological stability amidst changing environmental conditions. By contributing to the existing body of knowledge, our study advances the field of ecological science, enhancing the comprehension of predator-prey dynamics across diverse ecological conditions.
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  • 文章类型: Journal Article
    除了它们在统计热力学中的重要性,概率熵测量对于理解和分析复杂系统至关重要,在时间序列和一维剖面中具有不同的应用。然而,将这些方法扩展到二维和三维数据仍然需要进一步发展。在这项研究中,我们提出了一种基于熵测度的时空过程分类新方法。要测试和验证该方法,我们选择了与随机模式演化有关的五类类似过程:(i)白噪声;(ii)红噪声;(iii)从反应到扩散的弱湍流;(iv)流体动力学完全发展的湍流;(v)来自MHD的等离子体湍流。考虑从矩阵中测量熵的七种可能方法,我们将该方法呈现为由五个选定类的两个最佳分离度量组成的参数空间。结果突出了Shannon置换熵(SHp)的更好组合性能和基于Tsallis谱置换熵(Sqs)的新方法。值得注意的是,我们的观察揭示了在这个SHp×Sqs空间中反应项的分离,确定每一类动态过程的特定扇区的结果,并可用于训练机器学习模型,用于复杂时空模式的自动分类。
    In addition to their importance in statistical thermodynamics, probabilistic entropy measurements are crucial for understanding and analyzing complex systems, with diverse applications in time series and one-dimensional profiles. However, extending these methods to two- and three-dimensional data still requires further development. In this study, we present a new method for classifying spatiotemporal processes based on entropy measurements. To test and validate the method, we selected five classes of similar processes related to the evolution of random patterns: (i) white noise; (ii) red noise; (iii) weak turbulence from reaction to diffusion; (iv) hydrodynamic fully developed turbulence; and (v) plasma turbulence from MHD. Considering seven possible ways to measure entropy from a matrix, we present the method as a parameter space composed of the two best separating measures of the five selected classes. The results highlight better combined performance of Shannon permutation entropy (SHp) and a new approach based on Tsallis Spectral Permutation Entropy (Sqs). Notably, our observations reveal the segregation of reaction terms in this SHp×Sqs space, a result that identifies specific sectors for each class of dynamic process, and it can be used to train machine learning models for the automatic classification of complex spatiotemporal patterns.
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  • 文章类型: Journal Article
    通过q变形Sinh-Gordon方程的保形时间微分广义形式研究了量子变形中的孤子动力学和非线性现象。基础方程最近经历了大量的研究。在第1阶段,我们采用了改进的辅助和新的直接扩展代数方法。三角,双曲,使用这些技术成功地提取了指数解和有理解,加上对参数实施的最佳约束要求,以确保解的存在。调查结果,然后,用2D表示,3D和等高线图,以突出显示各种孤子传播模式,如扭结明亮,明亮,黑暗,明亮-黑暗,扭结,以及扭结峰孤子和孤波解。值得强调的是扭结黑暗,暗峰,黑暗和黑暗的亮孤子在早期文献中没有发现。在阶段2中,在各种混沌检测工具下检查底层模型,例如Lyapunov指数,多稳定性、时间序列分析和分岔图。使用各种初始条件研究了混沌行为,并获得了新的结果。
    Soliton dynamics and nonlinear phenomena in quantum deformation has been investigated through conformal time differential generalized form of q deformed Sinh-Gordon equation. The underlying equation has recently undergone substantial amount of research. In Phase 1, we employed modified auxiliary and new direct extended algebraic methods. Trigonometric, hyperbolic, exponential and rational solutions are successfully extracted using these techniques, coupled with the best possible constraint requirements implemented on parameters to ensure the existence of solutions. The findings, then, are represented by 2D, 3D and contour plots to highlight the various solitons\' propagation patterns such as kink-bright, bright, dark, bright-dark, kink, and kink-peakon solitons and solitary wave solutions. It is worth emphasizing that kink dark, dark peakon, dark and dark bright solitons have not been found earlier in literature. In phase 2, the underlying model is examined under various chaos detecting tools for example lyapunov exponents, multistability and time series analysis and bifurcation diagram. Chaotic behavior is investigated using various initial condition and novel results are obtained.
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  • 文章类型: Journal Article
    使用原始有限差分法对热辐射对某些纳米流体沿受热壁的自由对流的非线性影响进行了数值研究。纳米流体用于改善平坦和弯曲的集成光伏模块的性能。由于辐射项的强非线性,控制流量的偏微分方程很难求解。与以前的研究相比,通过Rosseland的非线性逼近,该问题无需线性化即可直接解决。用文献的结果验证了所提出的数值方法。非线性和各种物理参数如时间的影响,体积分数和辐射参数对速度的影响,温度,分析并给出了CuO-水纳米流体的努塞尔数和皮肤摩擦系数。通过对线性和非线性问题的解的比较研究表明,当热辐射的影响很大时,Rosseland的线性近似不再有效。另一方面,非线性模型更好地反映了冷却过程中涉及的物理现象。最后,五种纳米流体(CuO,Ag,水中的Al2O3,Cu和TiO2)表明Cu-水纳米流体表现最佳,具有高传热率和低剪切应力。
    The nonlinear effects of thermal radiation on the free convection flow of certain nanofluids along a heated wall are studied numerically using an original finite-difference method. Nanofluids are used to improve the performance of flat and curved integrated photovoltaic modules. The partial differential equations governing the flow are difficult to solve due to the strong non-linearity of the radiative term. In contrast to previous studies, the problem is solved directly without linearization by Rosseland\'s nonlinear approximation. The proposed numerical method is validated with results from the literature. The effects of nonlinearity and various physical parameters such as time, volume fraction and radiation parameter on the velocity, temperature, Nusselt number and skin friction coefficient of the CuO-water nanofluid are analyzed and presented graphically. A comparative study between the solutions given by the linear and non-linear problems reveals that Rosseland\'s linear approximation is no longer valid when the effect of thermal radiation is significant. On the other hand, the non-linear model better reflects the physical phenomena involved in the cooling process. Finally, a comparison of the performance of five nanofluids (CuO, Ag, Al2O3, Cu and TiO2 in water) shows that the Cu-water nanofluid performs best, with a high heat transfer rate and low shear stresses.
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