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North-Holland

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    Car-following characteristics and model of connected autonomous vehicles based on safe potential field

    Jia, YanfengQu, DayiSong, HuiWang, Tao...
    16页
    查看更多>>摘要：Aiming at the characteristics of connected and autonomous vehicle (CAV) which makes autonomous decision by perceiving the surrounding environment, a safe potential field model including lane marking potential field, road boundary potential field and vehicle potential field is established to describe the safe risk of CAV in the process of driving. In the process of building the safe potential field model, aiming at the defect that the existing vehicle potential field function has independent gravitational and repulsive expressions, a unified function of vehicle potential field based on Lennard-Jones potential is established by referring to the relationship of intermolecular interaction, and the parameter of vehicle's acceleration is considered into the vehicle potential field model. The statistical analysis of the parameter reveals that the change of acceleration directly affects the distribution of vehicle potential field and reflect the dynamic trend of vehicle's safe potential field under different driving states. Then, the safe potential field is applied to the car-following behavior of CAV, and the model's parameters are calibrated by Shanghai natural driving dataset; Finally, compared with the existing classic IDM and VTH models, the simulation results show that: the model still has smoother response curves in the three car-following scenarios designed to improve the safety and efficiency, which verifies the effectiveness of the model. The research results can lay a theoretical foundation for decision making behavior of safe driving, and also provide a unique way for the research of CAVs' safe technology. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Understanding the influencing factors of bicycle-sharing demand based on residents' trips

    Hu, BeibeiZhong, ZhenfangZhang, YanliSun, Yue...
    18页
    查看更多>>摘要：Bicycle-sharing is an eco-friendly transportation operating model in the context of "Internet Plus" and the sharing economy. It not only meets the short-distance travel needs of residents but has great significance for promoting the sustainable development of urban public transportation. However, a series of problems have appeared in the bicycle-sharing market, such as unreasonable resource allocation, low operating efficiency and management difficulties. Based on booking data and GPS trajectory data in Beijing of Mobike, this paper statistically analyzes the spatial and temporal distribution characteristics of residents' bicycle-sharing trips. Then, we construct a multi-factor influence model of bicycle-sharing demand based on a negative binomial regression and variable selection model, which quantifies a series of factors that influence bicycle-sharing trips, such as population and the regional economy, building land attributes, transportation accessibility, weather, and climatic conditions, etc. The results show that, firstly, there is a spatial imbalance in the distribution of bicycle-sharing demand among different districts in Beijing. Bicycle-sharing demand is mainly concentrated in the six core districts of the city, with more than 80% of all demand. We also find that the bicycle-sharing demand has different distribution characteristics on working days and nonworking days. Compared with nonworking days, residents' demand for bicycle-sharing on weekdays shows obvious peak periods in the morning, noon, and evening. Secondly, factors that have a major impact on the demand for bicycle-sharing include: per capita disposable income, pass facilities, parking lots etc. Among them, factors such as per capita disposable income, pass facilities, parking lots and bus/subway stations have a significant positive influence on bicycle-sharing demand. However, the number of functional zones such as airports, ports and marinas, tourist attraction and automobile sales has a significant negative influence. In addition, a comfortable temperature and good air quality encourage residents to use bicycle-sharing more for travel, while high humidity is not conducive to bicycle-sharing. We suggest that companies and related departments should jointly participate in the regulation and management of the bicycle-sharing industry, in various aspects such as bicycle scheduling, bicycle management and industry systems. In this way, cities can allocate bicycle-sharing resources reasonably and improve overall operating efficiency. The advantages of bicycle-sharing can be better used to promote the sustainable development of urban public transportation in the future. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Random matrix analysis of multiplex networks

    Raghav, TanuJalan, Sarika
    18页
    查看更多>>摘要：We investigate the spectra of adjacency matrices of multiplex networks under random matrix theory (RMT) framework. Through extensive numerical experiments, we demonstrate that upon multiplexing two random networks, the spectra of the combined multiplex network exhibit superposition of two Gaussian orthogonal ensemble (GOE)s for very small multiplexing strength followed by a smooth transition to the GOE statistics with an increase in the multiplexing strength. Interestingly, randomness in the connection architecture, introduced by random rewiring to 1D lattice, of at least one layer may govern nearest neighbor spacing distribution (NNSD) of the entire multiplex network, and in fact, can drive to a transition from the Poisson to the GOE statistics or vice versa. Notably, this transition transpires for a very small number of the random rewiring corresponding to the small-world transition. Ergo, only one layer being represented by the small-world network is enough to yield GOE statistics for the entire multiplex network. Spectra of adjacency matrices of underlying interaction networks have been contemplated to be related with dynamical behavior of the corresponding complex systems, the investigations presented here have implications in achieving better structural and dynamical control to the systems represented by multiplex networks against structural perturbation in only one of the layers. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Enhancing convergence efficiency of self-propelled agents using direction preference

    Chen, Yu-RongZhang, Xian-XiaYu, Yin-ShengMa, Shi-Wei...
    10页
    查看更多>>摘要：In this paper, we investigate the effect of direction preference on self-propelled agents. In the well-known Vicsek model, an agent treats its neighbors equally and updates its direction by the average direction of its neighbors. Whereas, in this study, agents prefer to synchronize with their neighbors moving in a certain direction, which is called preference direction. The center agent judges the influence value from its neighbor according to the direction angle between them. We assume that there exists a preference direction angle beta. When the direction angle between the neighbor and the center agent is closer to beta, the neighbor has greater influence on the center agent. The modified Vicsek model with preference direction angle is called direction preference model. We use the parameter alpha (0 < alpha <= 1) to adjust the effect of direction preference. The larger the value of alpha, the weaker the effect of direction preference. If alpha = 1, the direction preference will lose its effect. In the simulation experiments, different values of beta and alpha are discussed. Simulation results demonstrate that in noise-free environment the direction preference model with optimal beta = 3.7 pi /8 can accelerate the synchronization speed; in noise environment the direction preference model with beta be in [3 pi/8, 5 pi /8] has stronger robustness than the original Vicsek model and the optimal value of beta is altered. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Self-reliant cooling of ultracold atoms

    Du, JianyingFu, TongChen, JingyiSu, Shanhe...
    8页
    查看更多>>摘要：A self-reliant quantum cooler without an external control is proposed. To understand the thermal transport properties of the quantum system interacting with the baths described by the grand canonical ensemble, a two-level system with a single energy transport channel and a two-level coupled system with multi-channels are established. By considering the temperature dependence of the chemical potentials of the ultracold atom baths, the steady-state heat flows, particle currents, and entropy productions of these systems are derived. Results show that a steady heat current flows against the thermal bias for a nonequilibrium system coupled with ultracold quantum gases and the cooling rate can be enhanced by quantum coherence. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    Thermal fluctuations in a realistic ionic-crystal model

    Gangemi, RobertoCarati, AndreaGalgani, LuigiGangemi, Fabrizio...
    11页
    查看更多>>摘要：We investigate the thermal fluctuations of the ionic motions in a Born model of ionic crystals, namely, a model in which the electrons are eliminated, being replaced by suitable effective potentials among the ions. The model is studied in its classical version, computing the Newtonian trajectories of the ions. The general motivation is that, although being an essential ingredient within Green-Kubo linear response theory, thermal fluctuations apparently were not studied systematically by molecular dynamics methods, as was done instead for the approach to equilibrium in the Fermi-Pasta-Ulam problem. The time evolution of the fluctuations is studied in terms of the time-changes of the mode-energies of the system. The stages of the "regression" of the fluctuations are described, from a first stage of strong time-correlations up to a final decorrelation, and a comparison with the process of approach to equilibrium is performed. Finally, the dependence on specific energy is investigated. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier

    A complex network analysis approach for estimation and detection of traffic incidents based on independent component analysis

    Sheikh, Muhammad SameerRegan, Amelia
    21页
    查看更多>>摘要：Traffic incidents due to non-recurring congestion frequently occur in urban environments. In this study, we propose the estimation and detection of traffic incidents based on independent component analysis (ICA) and hybrid observer (HO)-generalized likelihood ratio (GLR) techniques. First, we develop the traffic time series to obtain insight into the traffic flow and to detect traffic incidents. Then, we use time series analysis to construct complex networks. Next, we propose the ICA technique to monitor traffic flow. Then, we introduce a piecewise switched linear model based observer to estimate the possible occurrence of traffic incidents. Finally, we propose a new incident detection method that combines HO and GLR techniques. The combined HO-GLR method can produce better incident detection, improve traffic safety, and enhance traffic management systems. We have validated the effectiveness of the proposed method using simulated traffic data generated from the Ayer Rajah Expressway in Singapore and a real-world dataset from the I-880 freeway of California. The performance metrics used to evaluate the performance of the proposed method includes detection rate, false alarm rate, classification rate, mean time to detection and the area under receiving operating characteristics curve. The experimental results show that the proposed method has obtained better performance in all of the criteria when compared with other well-known methods. (C) 2021 The Author(s). Published by Elsevier B.V.
      原文链接:
    • NSTL
    • Elsevier

    Degree distributions in AB random geometric graphs

    Stegehuis, ClaraWeedage, Lotte
    12页
    查看更多>>摘要：In this paper, we provide degree distributions for AB random geometric graphs, in which points of type A connect to the closest k points of type B. The motivating example to derive such degree distributions is in 5G wireless networks with multi-connectivity, where users connect to their closest k base stations. In this setting, it is important to know how many users a particular base station serves, which gives the degree of that base station. To obtain these degree distributions, we investigate the distribution of area sizes of the kth order Voronoi cells of B-points. Assuming that the A-points are Poisson distributed, we investigate the amount of users connected to a certain B-point, which is equal to the degree of this point. In the simple case where the B-points are placed in an hexagonal grid, we show that all kth order Voronoi areas are equal and thus all degrees follow a Poisson distribution. However, this observation does not hold for Poisson distributed B-points, for which we show that the degree distribution follows a compound Poisson-Erlang distribution in the 1-dimensional case. We then approximate the degree distribution in the 2-dimensional case with a compound Poisson-Gamma degree distribution and show that this one-parameter fit performs well for different values of k. Moreover, we show that for increasing k, these degree distributions become more concentrated around the mean. This means that k-connected AB random graphs balance the loads of B-type nodes more evenly as k increases. Finally, we provide a case study on real data of base stations. We show that with little shadowing in the distances between users and base stations, the Poisson distribution does not capture the degree distribution of these data, especially for k > 1. However, under strong shadowing, our degree approximations perform quite good even for these non-Poissonian location data. (C) 2021 The Author(s). Published by Elsevier B.V.
      原文链接:
    • NSTL
    • Elsevier

    The transition from generation-recombination noise in bulk semiconductors to discrete switching in small-area semiconductors (vol 568, 125748, 2021)

    Grueneis, Ferdinand
    2页
      原文链接:
    • NSTL
    • Elsevier

    Research on multilayer network structure characteristics from a higher-order model: The case of a Chinese high-speed railway system

    Ma, MengdiRen, CuipingXie, Fengjie
    16页
    查看更多>>摘要：In this paper, we integrate the non-Markovian higher-order model with the multilayer network analysis method for the first time to analyse the transportation system with route dependencies. An empirical study on the Chinese high-speed rail (HSR) system was conducted. The non-Markovian higher-order model is used to describe the theoretical high-speed railway network (THSRN), and weighted k-core decomposition is used to divide the THSRN into the core layer, bridge layer and periphery layer. We analyse the importance of cities and HSR routes. Ten important hub cities in the HSR system are discovered, and a finding against the common belief is revealed that the importance rank of cities is not completely consistent with their train flow. In addition, nine complete HSR lines and seven sections of the HSR lines were found to be the most important routes in the HSR system. Finally, the weaknesses of the HSR system are identified and some optimization suggestions are presented. Our work provides important insight for forming a new framework for analysing the transportation systems with route dependencies, which may assist in the future study of transportation systems. (C) 2021 Elsevier B.V. All rights reserved.
      原文链接:
    • NSTL
    • Elsevier