Journal of Statistical Mechanics: Theory and Experiment最新文献

{"title":"Collision-aware deflection model for boundary-constrained intersecting pedestrian streams","authors":"Zhonghao Zhan, Weiguo Song, Jun Zhang","doi":"10.1088/1742-5468/ad319c","DOIUrl":"https://doi.org/10.1088/1742-5468/ad319c","url":null,"abstract":"We propose a new model of boundary-constrained intersecting pedestrian flow based on the collision-free velocity model, named the collision-aware deflection model (CADM). The movement of pedestrians in the new model depends on the positions and velocities of other pedestrians ahead. A pedestrian walks in the desired direction at a free speed until an obstacle appears in the desired direction. When there is an obstacle in the desired direction, pedestrians tend to choose the direction with the smallest deflection angle. When the decision of a pedestrian conflicts with the movement of the nearest neighbor in front, the pedestrian stops moving. Comparing CADM with other models, the evacuation time of CADM during the simulation is very close to the time in the experiment. CADM also successfully reproduced the stripe phenomenon in boundary-constrained intersecting pedestrian streams, which was difficult to accomplish with the compared model. CADM also inherits several advantages of the original model, in that it can reproduce the corresponding self-organization phenomena in straight corridors and bottlenecks.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"59 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140611625","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}

{"title":"Variability of entropy force and its coupling with electrostatic and steric hindrance interactions","authors":"S Zhou","doi":"10.1088/1742-5468/ad363e","DOIUrl":"https://doi.org/10.1088/1742-5468/ad363e","url":null,"abstract":"We investigated the effective interaction potential (EIP) between charged surfaces in solvent comprised of dipole dimer molecules added with a certain amount of ionic liquid. Using classical density functional theory, the EIP is calculated and decoupled into entropic and energy terms. Unlike the traditional Asakura–Oosawa (AO) depletion model, the present entropic term can be positive or negative, depending on the entropy change associated with solvent molecule migration from bulk into slit pore. This is determined by pore congestion and disruption of the bulk dipole network. The energy term is determined by the free energy associated with hard-core repulsion and electrostatic interactions between surface charges, ion charges, and polarized charges carried by the dipole dimer molecules. The calculations in this article clearly demonstrate the variability of the entropy term, which contrasts sharply with the traditional AO depletion model, and the corrective effects of electrostatic and spatial hindrance interactions on the total EIP; we revealed several non-monotonic behaviors of the EIP and its entropic and energy terms concerning solvent bulk concentration and solvent molecule dipole moment; additionally, we demonstrated the promoting effect of dipolar solvent on the emergence of like-charge attraction, even in 1:1 electrolyte solutions. The microscopic origin of the aforementioned phenomena was analyzed to be due to the non-monotonic change of dipolar solvent adsorption with dipole moment under conditions of low solution dielectric constant. The present findings offer novel approaches and molecular-level guidance for regulating the EIP. This insight has implications for understanding fundamental processes in various fields, including biomolecule-ligand binding, activation energy barriers, ion tunneling transport, as well as the formation of hierarchical structures, such as mesophases, micro-, and nanostructures, and beyond.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"72 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140611542","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}

{"title":"Behavioral patterns of children during emergency evacuations: a comparative analysis of experimental observations and simulation results","authors":"Liang Chen, Chen Qiao, Jian Zhang, Chuan-Zhi (Thomas) Xie, Tie-Qiao Tang, Yanyan Chen","doi":"10.1088/1742-5468/ad363b","DOIUrl":"https://doi.org/10.1088/1742-5468/ad363b","url":null,"abstract":"This study investigates the behavioral patterns of children during emergency evacuations through a dual approach comprising controlled experimental evacuations within a classroom and computational modeling via a cellular automaton (CA) model. Observations from the experiments reveal several characteristic behaviors among children, including preferences for destinations, the impact of obstacles on their movement, as well as patterns of exit utilization, running and pushing during the evacuation process. Drawing upon these empirical findings, a CA model is developed to encapsulate these observed behaviors. A novel algorithm is introduced within this model to simulate the pushing behavior of children during emergency evacuations. Numerical simulations are conducted to validate the capability of the model to replicate the observed behaviors. The simulation results confirm that the model accurately reproduces the child behavior during evacuations. Furthermore, the results indicate that the total evacuation time is directly influenced by both the proportion of children exhibiting pushing behavior and the strength of the pushing force. These insights advance our understanding of child behavior in emergency situations and have significant implications for enhancing public safety.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"44 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140611624","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}

{"title":"Entropic relations for indistinguishable quantum particles","authors":"Marius Lemm","doi":"10.1088/1742-5468/ad343a","DOIUrl":"https://doi.org/10.1088/1742-5468/ad343a","url":null,"abstract":"The von Neumann entropy of a <italic toggle=\"yes\">k</italic>-body-reduced density matrix <italic toggle=\"yes\">γ</italic>\u0000_{\u0000<italic toggle=\"yes\">k</italic>\u0000} quantifies the entanglement between <italic toggle=\"yes\">k</italic> quantum particles and the remaining ones. In this paper, we rigorously prove general properties of this entanglement entropy as a function of <italic toggle=\"yes\">k</italic>; it is concave for all <inline-formula>\u0000<tex-math><?CDATA $1unicode{x2A7D} kunicode{x2A7D} N$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mn>1</mml:mn><mml:mtext>⩽</mml:mtext><mml:mi>k</mml:mi><mml:mtext>⩽</mml:mtext><mml:mi>N</mml:mi></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"jstatad343aieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> and non-decreasing until the midpoint <inline-formula>\u0000<tex-math><?CDATA $kunicode{x2A7D} lfloor{N/2} rfloor$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mi>k</mml:mi><mml:mtext>⩽</mml:mtext><mml:mo fence=\"false\" stretchy=\"false\">⌊</mml:mo><mml:mrow><mml:mi>N</mml:mi><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:mrow><mml:mo fence=\"false\" stretchy=\"false\">⌋</mml:mo></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"jstatad343aieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>. The results hold for indistinguishable quantum particles and are independent of the statistics.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"61 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140611546","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}

{"title":"Optimal finite-differences discretization for the diffusion equation from the perspective of large-deviation theory","authors":"Naftali R Smith","doi":"10.1088/1742-5468/ad363f","DOIUrl":"https://doi.org/10.1088/1742-5468/ad363f","url":null,"abstract":"When applying the finite-differences method to numerically solve the one-dimensional diffusion equation, one must choose discretization steps Δ<italic toggle=\"yes\">x</italic>, Δ<italic toggle=\"yes\">t</italic> in space and time, respectively. By applying large-deviation theory on the discretized dynamics, we analyze the numerical errors due to the discretization, and find that the (relative) errors are especially large in regions of space where the concentration of particles is very small. We find that the choice <inline-formula>\u0000<tex-math><?CDATA $Delta t = {Delta x}^2 / (6D)$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:mi>t</mml:mi><mml:mo>=</mml:mo><mml:msup><mml:mrow><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:mi>x</mml:mi></mml:mrow><mml:mn>2</mml:mn></mml:msup><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mo stretchy=\"false\">(</mml:mo><mml:mn>6</mml:mn><mml:mi>D</mml:mi><mml:mo stretchy=\"false\">)</mml:mo></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"jstatad363fieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>, where <italic toggle=\"yes\">D</italic> is the diffusion coefficient, gives optimal accuracy compared to any other choice (including, in particular, the limit <inline-formula>\u0000<tex-math><?CDATA $Delta t to 0$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:mi>t</mml:mi><mml:mo accent=\"false\" stretchy=\"false\">→</mml:mo><mml:mn>0</mml:mn></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"jstatad363fieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>), thus reproducing the known result that may be obtained using truncation error analysis. In addition, we give quantitative estimates for the dynamical lengthscale that describes the size of the spatial region in which the numerical solution is accurate, and study its dependence on the discretization parameters. We then turn to study the advection–diffusion equation, and obtain explicit expressions for the optimal Δ<italic toggle=\"yes\">t</italic> and other parameters of the finite-differences scheme, in terms of Δ<italic toggle=\"yes\">x</italic>, <italic toggle=\"yes\">D</italic> and the advection velocity. We apply these results to study large deviations of the area swept by a diffusing particle in one dimension, trapped by an external potential <inline-formula>\u0000<tex-math><?CDATA ${sim}|x|$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mrow><mml:mo>∼</mml:mo></mml:mrow><mml:mrow><mml:mo stretchy=\"false\">|</mml:mo></mml:mrow><mml:mi>x</mml:mi><mml:mo stretchy=\"false\">|</mml:mo></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"jstatad363fieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>. We extend our analysis to higher dimensions by combining our results from the one dimensional case with the locally one-dimension method.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"176 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140611543","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}

{"title":"Evolutionary accessibility of random and structured fitness landscapes","authors":"Joachim Krug, Daniel Oros","doi":"10.1088/1742-5468/ad3197","DOIUrl":"https://doi.org/10.1088/1742-5468/ad3197","url":null,"abstract":"Biological evolution can be conceptualized as a search process in the space of gene sequences guided by the fitness landscape, a mapping that assigns a measure of reproductive value to each genotype. Here, we discuss probabilistic models of fitness landscapes with a focus on their evolutionary accessibility, where a path in a fitness landscape is said to be accessible if the fitness values encountered along the path increase monotonically. For uncorrelated (random) landscapes with independent and identically distributed fitness values, the probability of existence of accessible paths between genotypes at a distance linear in the sequence length <italic toggle=\"yes\">L</italic> becomes nonzero at a nontrivial threshold value of the fitness difference between the initial and final genotypes, which can be explicitly computed for large classes of genotype graphs. The behaviour of uncorrelated random landscapes is contrasted with landscape models that display additional, biologically motivated structural features. In particular, landscapes defined by a tradeoff between adaptation to environmental extremes have been found to display a combinatorially large number of accessible paths to all local fitness maxima. We show that this property is characteristic of a broad class of models that satisfy a certain global constraint, and provide further examples from this class.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"59 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140592953","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}

{"title":"Coalescent processes emerging from large deviations","authors":"Ethan Levien","doi":"10.1088/1742-5468/ad2dda","DOIUrl":"https://doi.org/10.1088/1742-5468/ad2dda","url":null,"abstract":"The classical model for the genealogies of a neutrally evolving population in a fixed environment is due to Kingman. Kingman’s coalescent process, which produces a binary tree, emerges universally from many microscopic models in which the variance in the number of offspring is finite. It is understood that power-law offsprings distributions with infinite variance can result in a very different type of coalescent structure with merging of more than two lineages. Here, we investigate the regime where the variance of the offspring distribution is finite but comparable to the population size. This is achieved by studying a model in which the log offspring sizes have stretched exponential tails. Such offspring distributions are motivated by biology, where they emerge from a toy model of growth in a heterogeneous environment, but also from mathematics and statistical physics, where limit theorems and phase transitions for sums over random exponentials have received considerable attention due to their appearance in the partition function of Derrida’s random energy model (REM). We find that the limit coalescent is a <italic toggle=\"yes\">β</italic>-coalescent—a previously studied model emerging from evolutionary dynamics models with heavy-tailed offspring distributions. We also discuss the connection to previous results on the REM.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"50 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140593409","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}

{"title":"Dynamical theory of topological defects II: universal aspects of defect motion","authors":"Jacopo Romano, Benoît Mahault, Ramin Golestanian","doi":"10.1088/1742-5468/ad2ddb","DOIUrl":"https://doi.org/10.1088/1742-5468/ad2ddb","url":null,"abstract":"We study the dynamics of topological defects in continuum theories governed by a free energy minimization principle, building on our recently developed framework (Romano <italic toggle=\"yes\">et al</italic> 2023 <italic toggle=\"yes\">J. Stat. Mech.</italic> 083211). We show how the equation of motion of point defects, domain walls, disclination lines and any other singularity can be understood with one unifying mathematical framework. For disclination lines, this also allows us to study the interplay between the internal line tension and the interaction with other lines. This interplay is non-trivial, allowing defect loops to expand, instead of contracting, due to external interaction. We also use this framework to obtain an analytical description of two long-lasting problems in point defect motion, namely the scale dependence of the defect mobility and the role of elastic anisotropy in the motion of defects in liquid crystals. For the former, we show that the effective defect mobility is strongly problem-dependent, but it can be computed with high accuracy for a pair of annihilating defects. For the latter, we show that at the first order in perturbation theory, anisotropy causes a non-radial force, making the trajectory of annihilating defects deviate from a straight line. At higher orders, it also induces a correction in the mobility, which becomes non-isotropic for the <inline-formula>\u0000<tex-math><?CDATA $+1/2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mo>+</mml:mo><mml:mn>1</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"jstatad2ddbieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> defect. We argue that, due to its generality, our method can help to shed light on the motion of singularities in many different systems, including driven and active non-equilibrium theories.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"112 2 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315907","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}

{"title":"Dynamics of inertial particles under velocity resetting","authors":"Kristian Stølevik Olsen, Hartmut Löwen","doi":"10.1088/1742-5468/ad319a","DOIUrl":"https://doi.org/10.1088/1742-5468/ad319a","url":null,"abstract":"We investigate stochastic resetting in coupled systems involving two degrees of freedom, where only one variable is reset. The resetting variable, which we think of as hidden, indirectly affects the remaining observable variable via correlations. We derive the Fourier–Laplace transforms of the observable variable’s propagator and provide a recursive relation for all the moments, facilitating a comprehensive examination of the process. We apply this framework to inertial transport processes where we observe the particle position while the velocity is hidden and is being reset at a constant rate. We show that velocity resetting results in a linearly growing spatial mean squared displacement at later times, independently of reset-free dynamics, due to resetting-induced tempering of velocity correlations. General expressions for the effective diffusion and drift coefficients are derived as a function of the resetting rate. A non-trivial dependence on the rate may appear due to multiple timescales and crossovers in the reset-free dynamics. An extension that incorporates refractory periods after each reset is considered, where post-resetting pauses can lead to anomalous diffusive behavior. Our results are of relevance to a wide range of systems, such as inertial transport where the mechanical momentum is lost in collisions with the environment or the behavior of living organisms where stop-and-go locomotion with inertia is ubiquitous. Numerical simulations for underdamped Brownian motion and the random acceleration process confirm our findings.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"141 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315723","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}

{"title":"Epidemic process on partially overlapped multi-layer networks","authors":"Xin Jiang, Quanyi Liang","doi":"10.1088/1742-5468/ad2dd7","DOIUrl":"https://doi.org/10.1088/1742-5468/ad2dd7","url":null,"abstract":"The phenomenon of epidemic spread has received continuous attention due to its profound applications in a wide range of social and economic activities. In this paper we propose a partially overlapped multi-layer network model and illustrate the influence of multi-layer structure on outbreaks. Combined with the classic SIS model, we propose a set of discrete Markov equations and make first-order approximation on the threshold of epidemic outbreak. In comparison with independent simplex networks, we find that a multi-layer structure promotes epidemic spread and leads to a smaller critical threshold. In addition, we also find that the epidemic process on partially overlapped multi-layer networks is dominated by the layer with the largest main eigenvalue. Through Monte Carlo simulations, we find that the role of the dominant layer is irrelevant with its size, which means a small set of nodes can exhibit a disproportionate impact on the epidemics of a large network. Our research sheds light on the epidemic process on partially overlapped multi-layer complex systems, and provides a theoretical explanation of unexpected real-world outbreaks.","PeriodicalId":17207,"journal":{"name":"Journal of Statistical Mechanics: Theory and Experiment","volume":"55 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140315722","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}