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Behavior of Correlation Functions in the Dynamics of the Multiparticle Quantum Arnol’d Cat 多粒子量子阿诺德猫动力学中相关函数的行为
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-30 DOI: 10.3390/e26070572
Giorgio Mantica
The multi-particle Arnol’d cat is a generalization of the Hamiltonian system, both classical and quantum, whose period evolution operator is the renowned map that bears its name. It is obtained following the Joos–Zeh prescription for decoherence by adding a number of scattering particles in the configuration space of the cat. Quantization follows swiftly if the Hamiltonian approach, rather than the semiclassical approach, is adopted. The author has studied this system in a series of previous works, focusing on the problem of quantum–classical correspondence. In this paper, the dynamics of this system are tested by two related yet different indicators: the time autocorrelation function of the canonical position and the out-of-time correlator of position and momentum.
多粒子阿诺德猫是经典和量子哈密顿系统的广义化,其周期演化算子就是以其名字命名的著名映射。它是根据乔斯-泽赫的退相干处方,在猫的构型空间中增加一些散射粒子而得到的。如果采用哈密顿方法,而不是半经典方法,量子化就会迅速发生。作者在以前的一系列著作中研究过这个系统,重点是量子-经典对应问题。本文用两个相关但又不同的指标来检验这个系统的动力学:标准位置的时间自相关函数和位置与动量的时外相关器。
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引用次数: 0
Statistical Divergence and Paths Thereof to Socioeconomic Inequality and to Renewal Processes 统计分歧及其导致社会经济不平等和更新过程的路径
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-30 DOI: 10.3390/e26070565
Iddo Eliazar
This paper establishes a general framework for measuring statistical divergence. Namely, with regard to a pair of random variables that share a common range of values: quantifying the distance of the statistical distribution of one random variable from that of the other. The general framework is then applied to the topics of socioeconomic inequality and renewal processes. The general framework and its applications are shown to yield and to relate to the following: f-divergence, Hellinger divergence, Renyi divergence, and Kullback–Leibler divergence (also known as relative entropy); the Lorenz curve and socioeconomic inequality indices; the Gini index and its generalizations; the divergence of renewal processes from the Poisson process; and the divergence of anomalous relaxation from regular relaxation. Presenting a `fresh’ perspective on statistical divergence, this paper offers its readers a simple and transparent construction of statistical-divergence gauges, as well as novel paths that lead from statistical divergence to the aforementioned topics.
本文建立了测量统计发散的一般框架。即,对于具有共同取值范围的一对随机变量:量化一个随机变量的统计分布与另一个随机变量的统计分布之间的距离。然后,一般框架被应用于社会经济不平等和更新过程等主题。一般框架及其应用显示了以下内容的产生和关联:F-发散、海林格发散、仁义发散和库尔贝-莱布勒发散(也称为相对熵);洛伦兹曲线和社会经济不平等指数;基尼指数及其泛化;更新过程与泊松过程的发散;以及异常松弛与规则松弛的发散。本文以 "全新 "的视角介绍了统计发散,为读者提供了简单而透明的统计发散量规构造,以及从统计发散通向上述主题的新路径。
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引用次数: 0
Efficient and Flexible Method for Reducing Moderate-Size Deep Neural Networks with Condensation 高效灵活的凝缩式适度规模深度神经网络方法
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-30 DOI: 10.3390/e26070567
Tianyi Chen, Zhi-Qin John Xu
Neural networks have been extensively applied to a variety of tasks, achieving astounding results. Applying neural networks in the scientific field is an important research direction that is gaining increasing attention. In scientific applications, the scale of neural networks is generally moderate size, mainly to ensure the speed of inference during application. Additionally, comparing neural networks to traditional algorithms in scientific applications is inevitable. These applications often require rapid computations, making the reduction in neural network sizes increasingly important. Existing work has found that the powerful capabilities of neural networks are primarily due to their nonlinearity. Theoretical work has discovered that under strong nonlinearity, neurons in the same layer tend to behave similarly, a phenomenon known as condensation. Condensation offers an opportunity to reduce the scale of neural networks to a smaller subnetwork with a similar performance. In this article, we propose a condensation reduction method to verify the feasibility of this idea in practical problems, thereby validating existing theories. Our reduction method can currently be applied to both fully connected networks and convolutional networks, achieving positive results. In complex combustion acceleration tasks, we reduced the size of the neural network to 41.7% of its original scale while maintaining prediction accuracy. In the CIFAR10 image classification task, we reduced the network size to 11.5% of the original scale, still maintaining a satisfactory validation accuracy. Our method can be applied to most trained neural networks, reducing computational pressure and improving inference speed.
神经网络已被广泛应用于各种任务,并取得了惊人的成果。将神经网络应用于科学领域是一个重要的研究方向,越来越受到人们的关注。在科学应用中,神经网络的规模一般适中,主要是为了保证应用过程中的推理速度。此外,在科学应用中,将神经网络与传统算法进行比较是不可避免的。这些应用往往需要快速计算,因此缩小神经网络的规模变得越来越重要。现有研究发现,神经网络的强大功能主要归功于其非线性特性。理论研究发现,在强烈的非线性条件下,同一层中的神经元往往会表现出相似的行为,这种现象被称为凝聚。凝聚现象为缩小神经网络的规模,使其成为具有类似性能的更小的子网络提供了机会。在本文中,我们提出了一种浓缩缩减方法,以验证这一想法在实际问题中的可行性,从而验证现有理论。目前,我们的缩减方法既可用于全连接网络,也可用于卷积网络,并取得了积极的效果。在复杂的燃烧加速任务中,我们将神经网络的规模缩小到原来的 41.7%,同时保持了预测精度。在 CIFAR10 图像分类任务中,我们将网络规模缩小到原始规模的 11.5%,仍然保持了令人满意的验证精度。我们的方法可以应用于大多数训练有素的神经网络,从而减轻计算压力,提高推理速度。
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引用次数: 0
A Review of the Concept of Time Reversal and the Direction of Time 时间逆转和时间方向概念回顾
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-30 DOI: 10.3390/e26070563
Cristian López, Olimpia Lombardi
Abstract: In the debate about the direction of time in physics, the concept of time reversal has been central. Tradition has it that time-reversal invariant laws are sufficient to state that the direction of time is non-fundamental or emergent. In this paper, we review some of the debates that have gravitated around the concept of time reversal and its relation to the direction of time. We also clarify some of the central concepts involved, showing that the very concept of time reversal is more complex than frequently thought.
摘要:在物理学中关于时间方向的争论中,时间逆转的概念一直是核心问题。传统观点认为,时间反转不变定律足以说明时间方向是非基本的或突发的。在本文中,我们回顾了围绕时间反转概念及其与时间方向关系的一些争论。我们还澄清了其中涉及的一些核心概念,表明时间反转概念本身比人们通常认为的要复杂得多。
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引用次数: 0
Coherence-Enhanced Single-Qubit Thermometry out of Equilibrium 超出平衡状态的相干增强型单ubit测温仪
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-30 DOI: 10.3390/e26070568
Gonçalo Frazão, Marco Pezzutto, Yasser Omar, Emmanuel Zambrini Cruzeiro, Stefano Gherardini
The metrological limits of thermometry operated in nonequilibrium dynamical regimes are analyzed. We consider a finite-dimensional quantum system, employed as a quantum thermometer, in contact with a thermal bath inducing Markovian thermalization dynamics. The quantum thermometer is initialized in a generic quantum state, possibly including quantum coherence with respect to the Hamiltonian basis. We prove that the precision of the thermometer, quantified by the Quantum Fisher Information, is enhanced by the quantum coherence in its initial state. We analytically show this in the specific case of qubit thermometers for which the maximization of the Quantum Fisher Information occurs at a finite time during the transient thermalization dynamics. Such a finite-time precision enhancement can be better than the precision that is achieved asymptotically.
本文分析了在非平衡态下进行测温的计量极限。我们考虑了一个作为量子温度计使用的有限维量子系统,该系统与诱导马尔可夫热化动力学的热浴接触。量子温度计在一般量子态中初始化,可能包括与哈密顿基础相关的量子相干性。我们证明,温度计的精度(以量子费雪信息量化)会因其初始状态的量子相干性而增强。我们在量子比特温度计的特定情况下分析表明了这一点,对于这种温度计,量子费雪信息的最大化发生在瞬态热化动力学的有限时间内。这种有限时间精度的提高可能优于渐进达到的精度。
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引用次数: 0
Study on the Stability of Complex Networks in the Stock Markets of Key Industries in China 中国重点行业股票市场复杂网络的稳定性研究
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-30 DOI: 10.3390/e26070569
Zinuoqi Wang, Guofeng Zhang, Xiaojing Ma, Ruixian Wang
Investigating the significant “roles” within financial complex networks and their stability is of great importance for preventing financial risks. On one hand, this paper initially constructs a complex network model of the stock market based on mutual information theory and threshold methods, combined with the closing price returns of stocks. It then analyzes the basic topological characteristics of this network and examines its stability under random and targeted attacks by varying the threshold values. On the other hand, using systemic risk entropy as a metric to quantify the stability of the stock market, this paper validates the impact of the COVID-19 pandemic as a widespread, unexpected event on network stability. The research results indicate that this complex network exhibits small-world characteristics but cannot be strictly classified as a scale-free network. In this network, key roles are played by the industrial sector, media and information services, pharmaceuticals and healthcare, transportation, and utilities. Upon reducing the threshold, the network’s resilience to random attacks is correspondingly strengthened. Dynamically, from 2000 to 2022, systemic risk in significant industrial share markets significantly increased. From a static perspective, the period around 2019, affected by the COVID-19 pandemic, experienced the most drastic fluctuations. Compared to the year 2000, systemic risk entropy in 2022 increased nearly sixtyfold, further indicating an increasing instability within this complex network.
研究金融复杂网络中的重要 "角色 "及其稳定性对防范金融风险具有重要意义。一方面,本文基于互信息理论和阈值方法,结合股票收盘价收益率,初步构建了股市复杂网络模型。然后分析该网络的基本拓扑特征,并通过改变阈值来检验其在随机攻击和定向攻击下的稳定性。另一方面,本文利用系统风险熵作为量化股票市场稳定性的指标,验证了 COVID-19 大流行病这一广泛的突发事件对网络稳定性的影响。研究结果表明,这一复杂网络具有小世界特征,但不能严格归类为无标度网络。在这个网络中,工业部门、媒体和信息服务、制药和医疗保健、交通和公用事业发挥着关键作用。降低阈值后,网络对随机攻击的抵御能力也相应增强。从动态角度看,从 2000 年到 2022 年,重要工业股票市场的系统性风险显著增加。从静态角度看,受 COVID-19 大流行影响,2019 年前后的波动最为剧烈。与 2000 年相比,2022 年的系统性风险熵增加了近 60 倍,进一步表明这一复杂网络的不稳定性在增加。
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引用次数: 0
Machine Learning Classifier-Based Metrics Can Evaluate the Efficiency of Separation Systems 基于机器学习分类器的指标可评估分离系统的效率
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-30 DOI: 10.3390/e26070571
Éva Kenyeres, Alex Kummer, János Abonyi
This paper highlights that metrics from the machine learning field (e.g., entropy and information gain) used to qualify a classifier model can be used to evaluate the effectiveness of separation systems. To evaluate the efficiency of separation systems and their operation units, entropy- and information gain-based metrics were developed. The receiver operating characteristic (ROC) curve is used to determine the optimal cut point in a separation system. The proposed metrics are verified by simulation experiments conducted on the stochastic model of a waste-sorting system. Machine learning classifier-based metrics has promising potential to gain information about the performance of separation systems. Industrial separation systems can be considered to perform a classification task. Initialized by this analogy, existing metrics from the machine learning field (e.g., entropy and information gain) to qualify a classifier can be used to evaluate the effectiveness of these systems. Our research investigates this idea generally, and also introduces a case study of an industrial manual waste-sorting system. The contributions of the paper are the following: (1) Overview of the possible applications of classifier-based metrics for process development aims. (2) Entropy and information gain are shown to be applicable to evaluate the efficiency of separation systems and their operation units as well. (3) Monte Carlo simulation is involved to produce robust results in a separation system with stochastic phenomena. (4) The ROC curve is shown to be applicable to determining the optimal cut point in a separation system. The ideas above are verified by simulation experiments conducted on the stochastic model of a waste-sorting system.
本文强调,机器学习领域用于鉴定分类器模型的指标(如熵和信息增益)可用于评估分离系统的有效性。为了评估分离系统及其操作单元的效率,开发了基于熵和信息增益的指标。接收者操作特征曲线(ROC)用于确定分离系统的最佳切点。在垃圾分类系统的随机模型上进行的模拟实验验证了所提出的指标。基于机器学习分类器的度量方法有望获得有关分离系统性能的信息。工业分类系统可被视为执行分类任务。从这个类比出发,机器学习领域中用于鉴定分类器的现有指标(如熵和信息增益)可用于评估这些系统的有效性。我们的研究从总体上探讨了这一想法,并引入了一个工业人工垃圾分类系统的案例研究。本文的贡献如下:(1) 概述基于分类器的指标在流程开发目标中的可能应用。(2) 表明熵和信息增益也适用于评估分离系统及其操作单元的效率。(3) 在具有随机现象的分离系统中,采用蒙特卡罗模拟产生稳健的结果。(4) ROC 曲线适用于确定分离系统的最佳切点。通过对垃圾分类系统的随机模型进行模拟实验,验证了上述观点。
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引用次数: 0
Energy, Exergetic, and Thermoeconomic Analyses of Hydrogen-Fueled 1-kW Proton-Exchange Membrane Fuel Cell 氢燃料 1 千瓦质子交换膜燃料电池的能量、能效和热经济分析
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-30 DOI: 10.3390/e26070566
Yungpil Yoo, Sang-Yup Lee, Seok-Ho Seo, Si-Doek Oh, Ho-Young Kwak
Exergy analysis evaluates the efficiency of system components by quantifying the rate of entropy generation. In general, the exergy destruction rate or irreversibility rate was directly obtained through the exergy balance equation. However, this method cannot determine the origin of the component’s entropy generation rate, which is a very important factor in system design and improvement. In this study, a thorough energy, exergy, and thermoeconomic analysis of a proton-exchange membrane fuel cell (PEMFC) was performed, providing the heat transfer rate, entropy generation rate, and cost loss rate of each component. The irreversibility rate of each component was obtained by the Gouy–Stodola theorem. Detailed and extensive exergy and thermoeconomic analyses of the PEMFC system determined that water cooling units experience the greatest heat transfer among the components in the studied PEMFC system, resulting in the greatest irreversibility and, thus, the greatest monetary flow loss.
放能分析通过量化熵的产生率来评估系统组件的效率。一般来说,放能破坏率或不可逆率是通过放能平衡方程直接获得的。然而,这种方法无法确定组件熵产生率的来源,而熵产生率是系统设计和改进中一个非常重要的因素。本研究对质子交换膜燃料电池(PEMFC)进行了全面的能量、放能和热经济分析,提供了各组件的传热率、熵产生率和成本损失率。通过 Gouy-Stodola 定理得出了每个组件的不可逆率。对 PEMFC 系统进行的详细而广泛的放能和热经济分析表明,在所研究的 PEMFC 系统中,水冷却装置经历的热传递最大,导致不可逆性最大,因此货币流损失也最大。
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引用次数: 0
Statistical Interdependence between Daily Precipitation and Extreme Daily Temperature in Regions of Mexico and Colombia 墨西哥和哥伦比亚地区日降水量与日极端气温之间的统计相互依存关系
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-29 DOI: 10.3390/e26070558
Álvaro Zabaleta-Ortega, Teobaldis Mercado-Fernández, Israel Reyes-Ramírez, Fernando Angulo-Brown, Lev Guzmán-Vargas
We study the statistical interdependence between daily precipitation and daily extreme temperature for regions of Mexico (14 climatic stations, period 1960–2020) and Colombia (7 climatic stations, period 1973–2020) using linear (cross-correlation and coherence) and nonlinear (global phase synchronization index, mutual information, and cross-sample entropy) synchronization metrics. The information shared between these variables is relevant and exhibits changes when comparing regions with different climatic conditions. We show that precipitation and temperature records from La Mojana are characterized by high persistence, while data from Mexico City exhibit lower persistence (less memory). We find that the information exchange and the level of coupling between the precipitation and temperature are higher for the case of the La Mojana region (Colombia) compared to Mexico City (Mexico), revealing that regions where seasonal changes are almost null and with low temperature gradients (less local variability) tend to display higher synchrony compared to regions where seasonal changes are very pronounced. The interdependence characterization between precipitation and temperature represents a robust option to characterize and analyze the collective dynamics of the system, applicable in climate change studies, as well as in changes not easily identifiable in future scenarios.
我们利用线性(交叉相关性和一致性)和非线性(全球相位同步指数、互信息和跨样本熵)同步指标,研究了墨西哥(14 个气候站,1960-2020 年)和哥伦比亚(7 个气候站,1973-2020 年)地区日降水量和日极端气温之间的统计相互依存关系。在比较不同气候条件的地区时,这些变量之间共享的信息是相关的,并且会发生变化。我们发现,拉莫哈纳的降水和温度记录具有高持久性的特点,而墨西哥城的数据则表现出较低的持久性(记忆较少)。我们发现,拉莫哈纳地区(哥伦比亚)与墨西哥城(墨西哥)相比,降水和气温之间的信息交换和耦合程度更高,这表明季节变化几乎为零且气温梯度较低(局部变异性较小)的地区往往比季节变化非常明显的地区显示出更高的同步性。降水和气温之间的相互依存关系是描述和分析系统整体动态的一个可靠选择,适用于气候变化研究,以及在未来情景中不易识别的变化。
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引用次数: 0
Fast Finite-Time Observer-Based Event-Triggered Consensus Control for Uncertain Nonlinear Multiagent Systems with Full-State Constraints 针对具有全状态约束条件的不确定非线性多代理系统的基于事件触发的快速有限时间观测器共识控制
IF 2.7 3区 物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY Pub Date : 2024-06-29 DOI: 10.3390/e26070559
Kewei Zhou, Xin Wang
This article studies a class of uncertain nonlinear multiagent systems (MASs) with state restrictions. RBFNNs, or radial basis function neural networks, are utilized to estimate the uncertainty of the system. To approximate the unknown states and disturbances, the state observer and disturbance observer are proposed to resolve those issues. Moreover, a fast finite-time consensus control technique is suggested in order to accomplish fast finite-time stability without going against the full-state requirements. It is demonstrated that every signal could be stable and boundless, and an event-triggered controller is considered for the saving of resources. Ultimately, the simulated example demonstrates the validity of the developed approach.
本文研究了一类具有状态限制的不确定非线性多代理系统(MAS)。利用 RBFNN(即径向基函数神经网络)来估计系统的不确定性。为了逼近未知状态和扰动,文章提出了状态观测器和扰动观测器来解决这些问题。此外,还提出了一种快速有限时间共识控制技术,以便在不违背全状态要求的情况下实现快速有限时间稳定性。结果表明,每个信号都是稳定的、无边界的,并考虑采用事件触发控制器以节省资源。最终,模拟实例证明了所开发方法的有效性。
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引用次数: 0
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Entropy
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