Cornes, F. E.Sticco, I. M.Dorso, C. O.Rozan, E. A....
21页查看更多>>摘要：This research explores the dynamics of emergency evacuations in the presence of social groups. The investigation was carried out in the context of the Social Force Model (SFM). We included attractive feelings between individuals belonging to the same social group, as proposed in Ref. Frank and Dorso (2016). We focused on the escaping dynamics through an emergency exit and through a corridor. We confirmed the results appearing in Ref. Frank and Dorso (2016) for a desired velocity of 4 m/s, but further extended the analysis on the emergency exit to the range 1-8 m/s. We noticed that the presence of groups worsens the evacuation performance. However, very strong feelings can improve the escaping time with respect to moderate feelings. We call this phenomenon "Closer Is-Faster ", in analogy to the "Faster-Is-Slower " effect. The presence of social groups also affects the dynamics within a corridor by introducing an additional slow-down in the moving crowd.(C) 2022 Elsevier B.V. All rights reserved.
原文链接:
NSTL
Elsevier
Toman, KellanVoulgarakis, Nikolaos K.
13页查看更多>>摘要：Many predator species attempt to locate prey by following seemingly random paths. Although the underlying physical mechanism of the search remains largely unknown, such search paths are usually modeled by some type of random walk. Here, we introduce the stochastic pursuit-evasion equations that consider the bidirectional interaction between predators and prey. This assumption results in a modulated persistent random walk that is characterized by three interesting properties: power-law or tempered power-law distributed running times, superdiffusive or transient superdiffusive dynamics, and strong directional persistence. Furthermore, the proposed model exhibits a transition from Brownian to Levy-like motion with intensifying predator-prey interaction. Interestingly, persistent random walks with pure-power law distributed running times emerge at the limit of highest predator-prey interaction. We hypothesize that the system ultimately self-organizes into a critical interaction to avoid extinction. (c) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Enayat, TahaArdebili, Mohsen MehraniKivi, Ramtin ReyhaniAmjadi, Bahador...
15页查看更多>>摘要：How does society work? How do groups emerge within society? What are the effects of emotions and memory on our everyday actions? George Homans, like us, had a perspective on what society is, except that he was a sociologist. Homans theory, which is an exchange theory, is based on a few propositions about the fundamental actions of individuals, and how values, memory, and expectations affect their behavior. In this paper, as Homans predicted, our main interest and purpose are to find out whether these propositions lead to the emergence of groups. To do so, computationally, Based on Homans' prepositions, we provide the opportunity for each agent to exchange with other agents. That is, each agent transacts with familiar agents based on his previous history with them and transacts with newly found agents through exploration. The importance of our work is that we have scrutinized the consequences of an actual sociological theory through the eyes of simulation. At the end of our investigation, we discuss other possible directions for further research. (C) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Kotak, Jesal D.Barma, Mustansir
15页查看更多>>摘要：We study the competition between field-induced transport and trapping in a disordered medium by studying biased random walks on random combs and the bond-diluted Bethe lattice above the percolation threshold. While it is known that the drift velocity vanishes above a critical threshold, here our focus is on fluctuations, characterized by the variance of the transit times. On the random comb, the variance is calculated exactly for a given realization of disorder using a 'forward transport' limit which prohibits backward movement along the backbone but allows an arbitrary number of excursions into random-length branches. The disorder-averaged variance diverges at an earlier threshold of the bias, implying a regime of anomalous fluctuations, although the velocity is nonzero. Our results are verified numerically using a Monte Carlo procedure that is adapted to account for ultra-slow returns from long branches. On the Bethe lattice, we derive an upper bound for the critical threshold bias for anomalous fluctuations of the mean transit time averaged over disorder realizations. Finally, as for the passage to the vanishing velocity regime, it is shown that the transition to the anomalous fluctuation regime can change from continuous to first order depending on the distribution of branch lengths. (C) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Qi, HangYao, YingZhao, XiaohuaGuo, Jingfeng...
18页查看更多>>摘要：In light of the increasing amount of traffic disorder at road traffic hubs, to improve traffic safety, it is essential to detect road risks in advance and analyze the causes after its occurrence. In this study, interpretable machine learning (ML) is employed to analyze the traffic order by using a set of multi-source data comprising traffic conditions, traffic control devices, road conditions, and external conditions. Data were collected from the exits of some Beijing expressways via navigation and field investigations. The traffic order index (TOI) based on aggregate driving behavior data is used as a new surrogate index to evaluate the safety risk. A traffic order prediction model is then constructed by adapting the eXtreme Gradient Boosting (XGBoost) ML method. In addition, SHapley Additive exPlanation (SHAP) is employed to interpret the results and explore the relationships between the influencing factors and the traffic order. The results indicate that XGBoost could predict the traffic order levels well, and achieved an accuracy, precision, recall, and F-1-score of 92.62%, 92.67%, 92.62%, and 92.63%, respectively. The congestion index was found to have a great influence on traffic order. Furthermore, the number of lanes, advance guide signs, and weather conditions can have different effects on the traffic order under different traffic conditions. (C) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Mayo, M.Brey, J. Javierde Soria, M. I. GarciaMaynar, P....
12页查看更多>>摘要：A dilute gas of hard disks confined between two straight parallel lines is considered. The distance between the two boundaries is between one and two particle diameters, so that the system is quasi-one-dimensional. A Boltzmann-like kinetic equation, that takes into account the limitation in the possible scattering angles, is derived. It is shown that the equation verifies an H-theorem implying a monotonic approach to equilibrium. The implications of this result are discussed, and the equilibrium properties are derived. Closed equations describing how the kinetic energy is transferred between the degrees of freedom parallel and perpendicular to the boundaries are derived for states that are homogeneous along the direction of the boundaries. The theoretical predictions agree with results obtained by means of Molecular Dynamics simulations. (C) 2022 The Author(s). Published by Elsevier B.V.
原文链接:- NSTL
- Elsevier
Yang, YunMa, ChangxiLing, Gang
14页查看更多>>摘要：In order to avoid the huge hidden dangers caused by emergencies, it is particularly vital to make a reasonable pre-location and layout of emergency logistics facilities. A multi objective pre-location model of temporary distribution station for emergency materials was built, which considered the problems of information shortage and uncertain demand after the incident with minimum time, maximum time satisfaction, minimum delivery cost and psychological trauma to the masses. The priority of candidate points was solved by comprehensive evaluation methods, the nominal demand of served points was estimated by triangular fuzzy number theory (TFN), and the location model was solved by non-dominated sorting genetic algorithm. In addition, the optimal schemes without priority and considering it were compared and analyzed, the practicability of the model is verified by concrete examples. The results show the time and cost reduction of 7.754% and 25.651%, an increment of total satisfaction value of the scheme considering location priority. Therefore, the model and algorithm provide theoretical support and practical ideas for solving the location problem, which can better complete the task of the location problem for temporary distribution stations of urban emergency materials. (C) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Lai, XinBai, ShuliangLin, Yong
13页查看更多>>摘要：Complex network is a mainstream form of unstructured data in real world. Detecting communities in complex networks bears a wide range of applications. Different from the existing methods, which concentrate on applying statistics, graph theory or combinations, this work presents a new algorithm along a geometric avenue. By utilizing normalized discrete Ricci flow with modified sigma-weight-sum, and employing a limit-free Ricci curvature using *-coupling, this algorithm prevents the graph from collapsing to a point, and eliminates a hyper parameter alpha in discrete Ollivier Ricci curvature. Besides, experiments on real-world networks and artificial networks have shown that this normalized algorithm has a matching or better result, and is more robust with regard to unnormalized one (Ni et al., 2019). The code is available at https://github.com/laiguzi/NormalizedRicciFlow. (C) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Chen, ZhengLiu, JieyuLi, LiWu, Yongping...
12页查看更多>>摘要：Climate change has resulted in instability of semi-arid ecosystems under global warming, especially during the last decades. Hulun Buir Grassland is suffering from prominent warming and drying. Therefore, it is vital to research the change of climate factors such as precipitation, temperature and carbon dioxide concentrations [CO2] on vegetation dynamics. A vegetation-climate dynamic model is applied in a typical semi-arid area of Hulun Buir Grassland in China to research the effects on vegetation distribution due to climate change. Various climate scenarios with representative concentration pathways (Current, RCP2.6, RCP4.5, RCP8.5) are compared. Temperature, precipitation and CO2 fertilization effects play critical roles on vegetation growth. The vegetation pattern shows the synergies of temperature, precipitation and [CO2]. From our research, the vegetation pattern here may change from dense spot state to bare state. The ecosystem shows the fastest degradation under Current scenario, suggesting that Current scenario is the worst climate condition for vegetation growth there. However, the RCP2.6 scenario is an ideal climate state for vegetation growth in which the radiative forcing is low, precipitation increases slightly, and vegetation can grow well. (C) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
