Physica A: Statistical Mechanics and its Applications最新文献

英文中文

Optimal performance of irreversible quantum Stirling refrigerator with extreme relativistic particles as working substance

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-24 DOI: 10.1016/j.physa.2025.130486

Yong Yin , Xinting Fang , Lingen Chen , Yanlin Ge

In the context of finite-time thermodynamics (FTT), an irreversible quantum Stirling refrigerator (IQSR) model is constructed using extreme relativistic particles (ERP) confined within a one-dimensional infinite potential well (ODIPW) as the working medium. The cycle model is made up of two isothermal processes and two equal-L processes, where L is the width of the potential well, and the equal-L processes are treated as quantum isocapacitive processes. The occupation probability of the particles in an energy level follows the Gibbs distribution. Analytical formulas of coefficient of performance (COP, ε), cooling load (R) and Ω function are calculated. The curve of ε versus R rate is loop-shaped. The optimal performance interval, determined by cooling load and COP, can be divided into two distinct parts. One part is the optimization interval determined by the Ω function and COP optimization criteria. This interval takes the higher ε into accountwhen considering the cooling load. For instance, the maximum ε = 0.6743 is obtained when x_mcop = 1.0371. The other part is the optimization interval determined by the optimization criteria of the Ω function and cooling load, which takes the higher R into account. The maximum R corresponds to R*_max = 0.2918 and x_mR = 1.1333. The analyses reveal that the Ω function plays a critical role in this optimization process by capturing the trade-off between COP and cooling load. The Ω function is designed to quantify the efficiency loss due to finite-time effects, thus providing a useful tool to optimize cycles in practical applications. For the quantum Stirling refrigerator, the maximum value of the Ω function (Ω_max = 0.2802) occurs when x_mΩ = 1.1013 and R*_mΩ = 0.2889.

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引用次数: 0

Will the technological singularity come soon? Modeling the dynamics of artificial intelligence development via multi-logistic growth process

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-24 DOI: 10.1016/j.physa.2025.130450

Guangyin Jin , Xiaohan Ni , Kun Wei , Jie Zhao , Haoming Zhang , Leiming Jia

We are currently in an era of escalating technological complexity and profound societal transformations, where artificial intelligence (AI) technologies exemplified by large language models (LLMs) have reignited discussions on the ‘Technological Singularity’. ‘Technological Singularity’ is a philosophical concept referring to an irreversible and profound transformation that occurs when AI capabilities surpass those of humans comprehensively. However, quantitative modeling and analysis of the historical evolution and future trends of AI technologies remain scarce, failing to substantiate the singularity hypothesis adequately. This paper hypothesizes that the development of AI technologies could be characterized by the superposition of multiple logistic growth processes. To explore this hypothesis, we propose a multi-logistic growth process model and validate it using two real-world datasets: AI Historical Statistics and Arxiv AI Papers. Our analysis of the AI Historical Statistics dataset assesses the effectiveness of the multi-logistic model and evaluates the current and future trends in AI technology development. Additionally, cross-validation experiments on the Arxiv AI Paper, GPU Transistor and Internet User dataset enhance the robustness of our conclusions derived from the AI Historical Statistics dataset. The experimental results reveal that around 2024 marks the fastest point of the current AI wave, and the deep learning-based AI technologies are projected to decline around 2035–2040 if no fundamental technological innovation emerges. Consequently, the technological singularity appears unlikely to arrive in the foreseeable future.

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引用次数: 0

Degree distribution and patches of the image horizontal visibility graph mapped from two-dimensional Thue–Morse words

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-24 DOI: 10.1016/j.physa.2025.130467

Jia Li, Min Niu

In this paper, we aim to study the image horizontal visibility graph of order

n

(IHVG

_{n}

) mapped from the 2D Thue–Morse words which also help us to understand their limit, i.e., 2D Thue–Morse sequence. Firstly, we map the series to complex networks by using the image horizontal visibility algorithm of order 4. Subsequently, using the iterative method and the construction of sequences, we obtain the exact analytic expressions of the degree distribution of the 2D Thue–Morse IHVG₄. Furthermore, we also investigate 3-order patches of the 2D Thue–Morse IHVG₄ and find that the patch profile converges to a constant. Finally, numerical simulations are used to verify that theoretical values of the degree distribution and patch profile are in agreement with the simulated values.

引用次数: 0

Percolating critical window for correlated scale-free networks

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-24 DOI: 10.1016/j.physa.2025.130441

L-H. Wang, Y-M. Du

In scale-free networks, correlations between degrees could be induced by the forbidding of multiple connections between hubs. In particular, for scale-free networks with

2 < λ < 3

, where there is a natural cut-off on degrees, such correlations naturally arise. This kind of correlation was usually ignored when considering the critical percolation in these networks. To quantify its effect on the behavior of critical percolation, we consider a scale-dependent truncation

N^{ζ}

, which characterizes the strength of the degree-degree correlations, and a degree truncation

N^{κ}

, which characterizes the scale influence. Based on this model, we first analyze the critical behavior of percolation phase transitions using message passing methods. Our finding suggests that in scale-free networks with

2 < λ < 3

, the critical window is

| q_{c} (N) - q_{c} (\infty) | \sim N^{- min (ζ / 2, κ) \times (3 - λ)}

, where

q_{c}

denotes the critical occupied probability of sites. This indicates the degree-degree correlation would modify the universal class of percolation transition, and this phenomenon is absent in scale-free networks with

3 < λ < 4

. These analytical results are then inspected by numerical simulations.

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引用次数: 0

Inequality in a model of capitalist economy

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-23 DOI: 10.1016/j.physa.2025.130457

Jhordan Silveira Borba , Sebastian Gonçalves , Celia Anteneodo

We analyze inequality aspects of the agent-based model of capitalist economy named Social Architecture of Capitalism that has been introduced by Ian Wright. The model contemplates two main types of agents, workers and capitalists, which can also be unemployed. Starting from a state where all agents are unemployed and possess the same initial wealth, the system, governed by a few simple rules, quickly self-organizes into two classes. After a transient, the model reproduces the statistics of many relevant macroeconomic quantities of real economies worldwide, notably the Boltzmann-Pareto regimes of the distributions of wealth and income. We perform extensive simulations testing the role of the model parameters (number of agents, total wealth, and salary range) on the resulting distribution of wealth and income, the social distribution of agents, and other stylized facts of the dynamics. Our main finding is that, according to the model, in an economy where total wealth is conserved and with a fixed average wage, the increase in wealth per capita comes with more inequality.

引用次数: 0

Entropy production of a quantum system in non-equilibrium environment: The effect of coherence

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-21 DOI: 10.1016/j.physa.2025.130445

Ze-Yu Liu, Yun-Jie Xia, Zhong-Xiao Man

In this work, we study the entropy production of a quantum system undergoing dissipation in a non-equilibrium environment with weak coherence. We show that the entropy production rate can be decomposed into three contributions that are related to the system’s population, the system’s coherence, and the environmental coherence. With a specific model, we demonstrate that the initial coherence of the environment always contributes positively to the entropy production rate when the system is initially prepared in the thermal state. Nevertheless, the components of the entropy production rate exhibit distinct dependence on environmental coherence and may take negative values in certain ranges. Additionally, we show that when both the system and the environment are initially in states with finite nonzero coherence, the phase difference therein can reduce the entropy production rate to a level below that observed in a purely thermal environment. The stochastic versions of entropy production rate and its decomposition forms are also established from the perspective of quantum trajectories. Our findings on entropy production in the non-equilibrium environment provide beneficial supplement to conventional research in the thermal environment and are helpful for the development of high-performance thermal quantum technologies.

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引用次数: 0

Enhancing stock ranking forecasting by modeling returns with heteroscedastic Gaussian Distribution

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-21 DOI: 10.1016/j.physa.2025.130442

Jiahao Yang , Ran Fang , Ming Zhang , Wenkai Zhang , Jun Zhou

Accurately selecting stocks with the highest returns is crucial for profitable investing. However, predicting stock price movements is challenging due to the high degree of randomness caused by factors such as market opacity, unexpected events, erratic trades, etc. Previous research has primarily focused on extracting more information from inputs to map to the observed returns, such as modeling the complex relations of different stocks. However, they overlooked the uncertainty of returns caused by the randomness market. To mitigate it, we propose a novel analytical framework. The starting point is that the stock returns follow some distributions, so the observed returns are samples from them, and the variances are the source of randomness. After analysis, past studies were equivalent regarding the returns of different stocks at each time following homoscedastic Gaussian distributions, aiming to predict the mean of these distributions. We find that the hypothesis to be unreasonable and extend these distributions to the heteroscedastic case, presenting a revised model structure and learning objectives. The proposed method aims to simultaneously predict the mean and the standard deviation of distributions from inputs, and the model is trained based on the maximum likelihood principle. Experiment results on the stock members of the CSI 100, 300, and 500 Chinese market indexes show significant improvements compared with the previous methods. The annualized return of the Top 20 stock portfolios improved absolutely 2%, 20%, and 50%, proving the effectiveness of our framework. We discuss the roles of the obtained mean and standard deviation in pursuing more profits, and we extend our theory to a more general form through mathematical derivation.

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引用次数: 0

Beyond traditional metrics: Redefining urban metro network vulnerability with redundancy assessment

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-20 DOI: 10.1016/j.physa.2025.130461

Kaveh Rezvani Dehaghani, Catherine Morency

Previous studies have predominantly analyzed Urban Metro Network (UMN) vulnerability from topological and functional perspectives, often neglecting the impact of disruptions on alternative route availability. This research introduces a novel redundancy-based vulnerability analysis, assessing the reduction in travel alternatives following disruptions. The Montreal UMN is used as a case study, utilizing General Transit Feed Specification (GTFS) data from the Montreal Transit Authority and trip data from the 2018 Montreal Origin-Destination survey. Using the open-source platform Transition, we simulate shortest transit routes for each trip, generate alternative routes, and compute travel times. We define one targeted and three random failure scenarios, selected from 100 simulations, to evaluate network vulnerability to various disruption types. Indicators are formulated, calculated, and compared across all scenarios. Each failure scenario involves a sequence of consecutive metro station disruptions, leading to complete network shutdown. Findings reveal that the metro network is significantly more vulnerable to targeted disruptions than random ones. Among all indicators, functional ones related to users' travel time show greater sensitivity to disruption type, be it targeted or random. Vulnerability indicators exhibit the most substantial changes during initial disruptions, highlighting their critical impact. Although traditional approaches (topological and functional) show a direct relationship between the number of disruptions and changes in vulnerability indicators, this is not true for the redundancy-based vulnerability indicator. In this case, the primary determinants are the locations of disrupted stations and the network's geometry, rather than the number of disruptions.

以往的研究主要从拓扑和功能角度分析城市地铁网络（UMN）的脆弱性，往往忽视了中断对替代路线可用性的影响。本研究引入了一种新颖的基于冗余的脆弱性分析方法，对中断后出行选择的减少进行评估。本研究以蒙特利尔 UMN 为案例，利用了蒙特利尔交通局提供的通用交通反馈规范（GTFS）数据和 2018 年蒙特利尔始发站-目的地调查的行程数据。利用开源平台 Transition，我们模拟了每个行程的最短交通路线，生成了替代路线，并计算了旅行时间。我们从 100 次模拟中选择了一个目标故障场景和三个随机故障场景，以评估网络对各种中断类型的脆弱性。我们制定、计算并比较了所有情景下的指标。每个故障场景都涉及一连串连续的地铁站中断，最终导致网络完全关闭。研究结果表明，地铁网络更容易受到定向中断的影响，而不是随机中断。在所有指标中，与用户旅行时间相关的功能性指标对定向或随机中断类型的敏感度更高。脆弱性指标在初始中断期间的变化最大，凸显了其关键影响。虽然传统方法（拓扑和功能）显示中断次数与脆弱性指标变化之间存在直接关系，但基于冗余的脆弱性指标并非如此。在这种情况下，主要决定因素是中断站点的位置和网络的几何形状，而不是中断次数。

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引用次数: 0

Hartree–Fock approximation for bosons with symmetry-adapted variational wave functions 具有对称调整变异波函数的玻色子的哈特里-福克近似

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-20 DOI: 10.1016/j.physa.2025.130449

B.R. Que , J.M. Zhang , H.F. Song , Y. Liu

The Hartree–Fock approximation for bosons employs variational wave functions that are a combination of permanents. These are bosonic counterpart of the fermionic Slater determinants, but with the significant distinction that the single-particle orbitals used to construct a permanent can be arbitrary and do not need to be orthogonal to each other. Typically, the variational wave function may break the symmetry of the Hamiltonian, resulting in qualitative and quantitative errors in physical observables. A straightforward method to restore symmetry is projection after variation, where we project the variational wave function onto the desired symmetry sector. However, a more effective strategy is variation after projection, which involves first creating a symmetry-adapted variational wave function and then optimizing its parameters. We have devised a scheme to realize this strategy and have tested it on various models with symmetry groups ranging from

Z_{2}

C_{L}

, to

D_{L}

. In all the models and symmetry sectors studied, the variational wave function accurately estimates not only the energy of the lowest eigenstate but also the single-particle correlation function, as it approximate the target eigenstate very well on the wave function level. We have applied this method to study few-body bound states, superfluid fraction, and Yrast lines of some Bose–Hubbard models. This approach should be valuable for studying few-body or mesoscopic bosonic systems.

{"title":"Hartree–Fock approximation for bosons with symmetry-adapted variational wave functions","authors":"B.R. Que , J.M. Zhang , H.F. Song , Y. Liu","doi":"10.1016/j.physa.2025.130449","DOIUrl":"10.1016/j.physa.2025.130449","url":null,"abstract":"<div><div>The Hartree–Fock approximation for bosons employs variational wave functions that are a combination of permanents. These are bosonic counterpart of the fermionic Slater determinants, but with the significant distinction that the single-particle orbitals used to construct a permanent can be arbitrary and do not need to be orthogonal to each other. Typically, the variational wave function may break the symmetry of the Hamiltonian, resulting in qualitative and quantitative errors in physical observables. A straightforward method to restore symmetry is projection after variation, where we project the variational wave function onto the desired symmetry sector. However, a more effective strategy is variation after projection, which involves first creating a symmetry-adapted variational wave function and then optimizing its parameters. We have devised a scheme to realize this strategy and have tested it on various models with symmetry groups ranging from <span><math><msub><mrow><mi>Z</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span>, <span><math><msub><mrow><mtext>C</mtext></mrow><mrow><mi>L</mi></mrow></msub></math></span>, to <span><math><msub><mrow><mtext>D</mtext></mrow><mrow><mi>L</mi></mrow></msub></math></span>. In all the models and symmetry sectors studied, the variational wave function accurately estimates not only the energy of the lowest eigenstate but also the single-particle correlation function, as it approximate the target eigenstate very well on the wave function level. We have applied this method to study few-body bound states, superfluid fraction, and Yrast lines of some Bose–Hubbard models. This approach should be valuable for studying few-body or mesoscopic bosonic systems.</div></div>","PeriodicalId":20152,"journal":{"name":"Physica A: Statistical Mechanics and its Applications","volume":"664 ","pages":"Article 130449"},"PeriodicalIF":2.8,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Platoon agglomeration strategy and analysis in CAV dedicated lanes under low CAV penetration

IF 2.8 3区物理与天体物理 Q2 PHYSICS, MULTIDISCIPLINARY

Physica A: Statistical Mechanics and its Applications

Pub Date : 2025-02-20 DOI: 10.1016/j.physa.2025.130471

Yongjie Zhou, Jun Liang

Platoon agglomeration is a key research focus aimed at enhancing road traffic efficiency and safety for Connected Human-driven Vehicles (CHVs) and Connected and Autonomous Vehicles (CAVs) in mixed traffic scenarios. Given the low utilization of CAV Dedicated Lanes (CDLs) caused by platoon agglomeration under low CAV penetration rates, coupled with challenges in ensuring safe and efficient vehicle operations, vehicle control methods for various scenarios were comprehensively analyzed, leading to the proposal of a Lane Level Mixed Agglomeration (LLMA) strategy. This strategy can select CAVs and CHVs that meet the agglomeration conditions to enter the CDL based on the designed vehicle agglomeration algorithm. Additionally, to accurately capture the driving characteristics of CHVs within the CDL under the LLMA strategy, a CHV molecular force field model was designed. This model incorporates a speed coordination term accounting for V2V real-time information and driver subjective perception, building upon the traditional molecular force field model. The results indicate that the LLMA strategy significantly enhances CDL utilization at low CAV penetration rates, increases road capacity and average vehicle speed, and reduces travel risk. This study offers theoretical insights for enhancing traffic efficiency and safety in CDL scenarios and plays a crucial role in advancing the practical implementation of connected autonomous driving technologies in future mixed traffic conditions.

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引用次数: 0

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