Effect of vertical grouping behavior on pedestrian evacuation efficiency

Grouping behavior is an important element which affects pedestrian group-moving behavior significantly. Current studies only give a few discussions on how grouping behavior affects pedestrian counter flow, while the effect of grouping behavior on evacuation flow is largely ignored. Here we propose a cellular automation model to describe pedestrian behavior under different grouping behavior in evacuation. By simulation we find that, comparing with other grouping behaviors, vertical grouping will block pedestrian transverse movement significantly, and this may cause pedestrians to appear as a two-peak arching distribution in the middle of evacuation and two-peak arching with a gap distribution near the end of evacuation. To the best of our knowledge, this is the first time these phenomena have been presented.     

A vehicle overtaking model of traffic dynamics

Mathematical models that describe the dynamical behavior of a group of vehicles as they move along a stretch of road are known as car following models. They attempt to model the interactions between individual vehicles where the behavior of each vehicle is dependent on the motion of the vehicle directly in front and overtaking is not permitted. In this paper, the traditional car following model is modified by removing this "no overtaking" restriction and its behavior is investigated for a group of vehicles traveling on a closed loop. The resulting model is described in terms of a set of coupled time delay differential equations, and these are solved numerically to analyze their post transient behavior under a periodic perturbation. The effect of varying both the time taken for the driver to respond to the behavior of the vehicle in front and the length of the closed loop is examined. For certain parameter choices, the post transient behavior is found to be chaotic, and in these cases the degree of chaos is estimated using the Grassberger-Procaccia dimension.     

Critical Behavior of the Kramers Escape Rate in Asymmetric Classical Field Theories

We introduce an asymmetric classical Ginzburg–Landau model in a bounded interval, and study its dynamical behavior when perturbed by weak spatiotemporal noise. The Kramers escape rate from a locally stable state is computed as a function of the interval length. An asymptotically sharp second-order phase transition in activation behavior, with corresponding critical behavior of the rate prefactor, occurs at a critical length ? _c , similar to what is observed in symmetric models. The weak-noise exit time asymptotics, to both leading and subdominant orders, are analyzed at all interval lengthscales. The divergence of the prefactor as the critical length is approached is discussed in terms of a crossover from non-Arrhenius to Arrhenius behavior as noise intensity decreases. More general models without symmetry are observed to display similar behavior, suggesting that the presence of a “phase transition” in escape behavior is a robust and widespread phenomenon.     

交替行为对螺旋波影响的数值模拟研究

在离散可激发介质Greenberg-Hasting模型中引入交替(alternans)行为,研究了交替行为对螺旋波的影响.数值结果表明:在适当选择参数下,交替对螺旋波有很大影响,例如交替导致螺旋波的形状振荡,形成呼吸螺旋波,交替使螺旋波漫游、漂移,甚至使螺旋波漫游出系统的边界,交替使螺旋波破碎形成小螺旋波、反靶波和时空混沌等,首次在均匀介质中观察到交替导致传导障碍,使螺旋波破碎和消失,并对发生这些现象的机理进行了分析. 关键词： 离散可激发介质 螺旋波 靶波 漫游     

Chaos in the long-term behavior of some Bianchi-type VIII models

The long-term behavior of Bianchi-type VIII models with three different types of stress-energy tensors are examined and compared. The vacuum model, a matter-filled model, and a model with an electromagnetic field are considered. In each case the existence of chaotic behavior and transitions to chaotic behavior are discussed.     

Dynamic Robustness of Open-Source Project Knowledge Collaborative Network Based on Opinion Leader Identification

A large amount of semantic content is generated during designer collaboration in open-source projects (OSPs). Based on the characteristics of knowledge collaboration behavior in OSPs, we constructed a directed, weighted, semantic-based knowledge collaborative network. Four social network analysis indexes were created to identify the key opinion leader nodes in the network using the entropy weight and TOPSIS method. Further, three degradation modes were designed for (1) the collaborative behavior of opinion leaders, (2) main knowledge dissemination behavior, and (3) main knowledge contribution behavior. Regarding the degradation model of the collaborative behavior of opinion leaders, we considered the propagation characteristics of opinion leaders to other nodes, and we created a susceptible–infected–removed (SIR) propagation model of the influence of opinion leaders’ behaviors. Finally, based on empirical data from the Local Motors open-source vehicle design community, a dynamic robustness analysis experiment was carried out. The results showed that the robustness of our constructed network varied for different degradation modes: the degradation of the opinion leaders’ collaborative behavior had the lowest robustness; this was followed by the main knowledge dissemination behavior and the main knowledge contribution behavior; the degradation of random behavior had the highest robustness. Our method revealed the influence of the degradation of collaborative behavior of different types of nodes on the robustness of the network. This could be used to formulate the management strategy of the open-source design community, thus promoting the stable development of OSPs.     

Dynamical mechanism of two-phase phenomena in financial markets

Two-phase behavior of the Korean treasury bond (KTB) futures in the Korean exchange market is investigated in this study. To show that the two-phase phenomena are due to heavy-tailed behavior of distribution of price returns, actual data from the KTB futures market with shuffled data and a generated time series are examined according to the Brownian process. In addition, we study the correlation inherent in the KTB futures and its Brownian walk, describing the extent to which the volatility clustering plays a crucial role in equilibrium and nonequilibrium states of financial markets. It is shown that the two-phase behavior essentially results from heavy-tailed behavior of the distribution of price returns. This two-phase behavior does not appear to be relevant to volatility clustering.     

Influence of long-range effects on the critical behavior of three-dimensional systems

The Padé-Borel resummation technique is used to describe field-theoretically, in the two-loop approximation, the behavior of Ising systems with long-range effects directly in a three-dimensional space. The renormalization-group equations are analyzed and the fixed points governing the critical behavior of the system are determined. It is shown that the long-range effects can bring about a change in both the regime of critical behavior and the kind of phase transition.     

An energy residual method for detection of the causes of vibration hypersensitivity

This work deals with hypersensitive vibration behavior of plates. The aim of the proposed method is to detect structural zones inducing such behavior. It is based on a residual calculation, which takes into account structural uncertainties, and has a low numerical cost since it requires only the resolution of the problem for the nominal structure. Then, this solution is used to calculate energy residuals on different parts of perturbed structures in order to detect which zones will produce an hypersensitive behavior. The basis of the method is first developed on a simple problem, a rod, and then applied to a typical hypersensitive structure, a plates network. Finally, one can show that the proposed tool is able to detect which zones of the plates network are responsible for hypersensitive behavior.     

粗糙铂电极上甲醛电氧化行为及其现场表面拉曼光谱研究

利用循环伏安法研究了酸性介质中甲醛在粗糙铂电极上电氧化行为 ,考察了支持电解质浓度 ,电极表面结构等因素对甲醛氧化行为的影响 ,发现了甲醛在粗糙铂电极上的自发解离现象。采用共焦显微拉曼技术研究了甲醛在粗糙铂电极上解离吸附行为 ,获得了甲醛在该电极表面解离吸附的分子水平信息 ,并且从分子水平验证了甲醛在粗糙铂电极上的自发解离现象。     

Statistical thermodynamics of block copolymers: Network statistics

The swelling behavior of a lamellar domain system of an ABA block copolymer is treated, with account taken of the relative population of the B chains as “loops” and “bridges.” The swelling behavior is not a sensitive function of these configurations, since both types in condensed systems are elastically effective, in contrast to the behavior of isolated chains.     

An effect of particle size on the behavior of ferromagnetic materials

The dependence of magnetic behavior of media upon the particle/grain size is studied here. A model is presented to describe the behavior of nanomagnetic materials as a function of particle size. The model is applied to two types of experiments: (1) the decay rate of the magnetic aftereffect in nanomagnets and (2) the variation of spontaneous magnetization versus temperature. Both of these experiments show a deviation from the behavior of bulk media above a critical temperature.     

Cooperative acceleration of task performance: Foraging behavior of interacting multi-robots system

We study the effectiveness of cooperative behavior in a society of interacting agents. After reviewing the problem and defining the concept of swarm intelligence, we examine collective behavior of many-body active clusters through a task to gather pucks in the field. In this study, we used a robot with a simple structure which has a driving system and the simplest interacting means; a light and some sensors. The effectiveness of group behavior was studied under various (homogeneous, localized) puck distributions with real experiment, simulation, and analysis. To evaluate the efficiency of group behavior, we examined the scaling relation between the task completion time and the number of robots, and the relation between the interaction period and the efficiency of group. We found that a cooperation between agents by a simple interaction is very efficient in enhancing the performance of the group compared with independent individuals.     

Clustering Effect on the Evolution of Cooperation in a Herding Snowdrift Game

We study the evolution of cooperation for two cluster breaking mechanisms in a herding snowdrift game. The cooperative behavior is observed to be related to the duster size. A negative dependence of the payoff parameter r on cooperative behavior is discovered. For a low r, herding helps promote the cooperation, whereas for a high r, herding tends to prevent cooperative behavior.     

Near-critical behavior for one-parameter families of circle maps

Past studies of systems showing mixed-mode oscillations have revealed behavior along arbitrarily chosen parameter paths similar to that on the critical surface marking the break-up of invariant tori. Observations of this behavior in a model of the Belousov-Zhabotinskii reaction is presented. Using the theory of circle maps, it is shown that near-critical behavior can arise along one-parameter paths.     

Oscillatory behavior of critical amplitudes of the Gaussian model on a hierarchical structure

We studied oscillatory behavior of critical amplitudes for the Gaussian model on a hierarchical structure presented by a modified Sierpinski gasket lattice. This model is known to display nonstandard critical behavior on the lattice under study. The leading singular behavior of the correlation length xi near the critical coupling K=K(c) is modulated by a function which is periodic in ln/ln(K(c)-K)/. We have also shown that the common finite-size scaling hypothesis, according to which for a finite system at criticality xi should be of the order of the size of the system, is not applicable in this case. As a consequence of this, the exact form of the leading singular behavior of xi differs from the one described earlier (which was based on the finite-size scaling assumption).     

Infrared behavior of interacting bosons at zero temperature

We review the infrared behavior of interacting bosons at zero temperature. After a brief discussion of the Bogoliubov approximation and the breakdown of perturbation theory due to infrared divergences, we present two approaches that are free of infrared divergences—Popov’s hydrodynamic theory and the nonperturbative renormalization group—and allow us to obtain the exact infrared behavior of the correlation functions. We also point out the connection between the infrared behavior in the superfluid phase and the critical behavior at the superfluid-Mott-insulator transition in the Bose-Hubbard model.     

Experimental and numerical study of the switching dynamics of Raman fiber lasers

We present an experimental and numerical survey of the switching behavior of cascaded Raman fiber lasers (RFLs). When these lasers are switched on, the output power shows a pulsing behavior where the pulse powers strongly exceed the steady-state output powers. The influence of the pump-laser and fiber properties of a RFL on this dynamical behavior is investigated both experimentally and numerically, where experiments and simulations showed good qualitative agreement. PACS 42.55.Wd; 42.55.Ye; 42.60.Lh