A novel algorithm of simulating multi-velocity evacuation based on cellular automata modeling and tenability condition

A cellular automata (CA) model, which adopts the findings of tenability analysis, is proposed to simulate the evacuation from a smoke-filled room. Two algorithms, viz., direct algorithm and indirect algorithm, are used to model the behavior of a crowd consisting of people with different movement velocities. In the indirect algorithm, the movement velocity is related to probability so that the CPU time is greatly reduced. Another novelty is that an experimental formula for estimating the survival duration when exposed to constant concentration of toxic gases in a static environment is extended to one that involves varying degree of toxic gases. This has been incorporated into the CA model.     

Study of bottleneck effect at an emergency evacuation exit using cellular automata model, mean field approximation analysis, and game theory

An improved cellular automaton model for pedestrian dynamics was established, where both static floor field and collision effect derived from game theory were considered. Several model parameters were carefully determined by previous studies. Results obtained through model-based simulation and analytical approach (derived from mean field approximation) proved that outflow rate from an evacuation exit, which is usually estimated using outflow coefficient in building codes in Japan, can be improved by placing an appropriate obstacle in front of the exit. This can reduce collision probability at the exit by increasing collisions around the obstacles ahead of the exit.     

Coarse-grained molecular dynamics simulations of capillary evaporation of water confined in hydrophilic mesopores

Non-equilibrium molecular dynamics (MD) simulations were performed to investigate the capillary evaporation of water confined in hydrophilic mesopores. The electrostatics-based (ELBA) coarse-grained water model was employed to calculate the duration of the time-consuming capillary evaporation process. To evaluate the effect of hydrophilicity of mesopores on the capillary evaporation of water, three types of thin films with a cylindrical mesopore were modelled by tuning the interactions between water and wall atoms. Initially, the cylindrical mesopore was filled with water, and evaporation of the water into vacuum was simulated. The calculation results showed that when capillary evaporation occurred, the desorption rate of water was almost constant in a highly hydrophilic mesopore where a stable water layer was formed on the pore surface, whereas the rate decreased with time in a weakly hydrophilic mesopore where the water layer did not remain stable. As time progressed, the water column shortened and then broke up. The number of water molecules in the mesopores decreased exponentially with time. The difference in the hydrophilicity of the mesopores resulted in different relaxation curves of water desorption from the mesopores.     

Molecular dynamics study of the vibrational relaxation of OCl and OCl in the bulk and the surface of water and acetonitrile

The vibrational relaxation of OCl and OCl⁻ in the bulk and the liquid/vapor interface of water and acetonitrile is studied by molecular dynamics computer simulations. Both equilibrium calculations of the vibrational friction and non-equilibrium simulation of the energy relaxation are used to elucidate the factors that influence the rate of energy relaxation in systems that represent polar ionic and non-ionic solutes in polar protic and non-protic solvents. We find that, in agreement with previous experimental and theoretical studies, the relaxation of the ionic solute is much faster than that of the non-ionic solute in both the solvents. However, while the relaxation is slowed down considerably when the non-ionic solute is transferred from the bulk to the interface, no such surface effect is found in the case of the ionic solute. This behavior can be explained by noting that the ionic solute is able to keep its first solvation shell intact upon transfer to the interface and that the main contribution to the friction is due to the Lennard-Jones part of the intermolecular potential.     

Chaotic dynamics in biological information processing: A heuristic outline

Summary A given but otherwise random environmental time series impinging on the input of a certain biological processor passes through with overwhelming probability practically undetected. A very small percentage of environmental stimuli, though, is ?captured? by the processor's nonlinear dissipative operator asinitial conditions, that is, assolutions of the processor's dissipative dynamics. The processor, then, is in such cases instrumental in compressing or abstracting those stimuli, thereby making the external world to collapse from a previous regime of a ?pure state? of suspended animation onto a set of stable eigenfunctions or ?categories?—chaotic strange attractors. The characteristics of this cognitive set depend on the operator involved and the hierarchical level where the abstraction takes place. In this paper we model the physics of such a cognitive process and the role that the thalamo-cortical pacemaker of the (human) brain plays in both stimulating the individual attractors and permutating them on a time division multiplexing basis. A synthesis of the Markovian processes taking place within each individual attractor-memory and the Markovian or semi-Markovian process involving the intermittent jumping among the different attractor-memories are discussed.

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Riassunto Una data ma casuale serie temporale ambientale che influisce sull'immissione di un determinato processore biologico passa con schiacciante probabilità praticamente inosservata. Una piccolissima percentuale di stimoli ambientali, tuttavia, è catturata dall'operatore dissipativo non lineare del processore comecondizioni iniziali, cioè comesoluzioni della dinamica dissipativa del processore. Il processore è quindi, in tali casi, strumentale nel comprimere o estrarre quegli stimoli, facendo perciò collassare il mondo esterno da un precedente regime di ?stato puro? ad animazione sospesa ad un gruppo di autofunzioni stabili o ?categorie?—attrattori caotici strani. Le caratteristiche di questo gruppo cognitivo dipendono dall'operatore coinvolto e dal livello gerarchico in cui l'estrazione ha luogo. In questo lavoro si modella la fisica di tale processo cognitivo e il ruolo che lo stimolatore talamo-corticale del cervello (umano) ha sia nello stimolare gli attrattori individuali che nel permutarli su una base che manda segnali multiplex a divisione temporale. Si discute una sintesi dei processi markoviani che hanno luogo all'interno di ogni attrattore-memoria individuale e il processo markoviano o semimarkoviano che interessa il salto intermittente tra i diversi attrattori-memoria.

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Резюме Временная последовательность на входе некоторого биологического процессора может иметь практически недетектируемую вероятность. Очень небольшой процент стимулов окружающей среды ?захватывается? нелинейным диссипативным оператором процессора как начальные условия, т.е. представляется как решение диссипативпой динамики процессора. Затем процессор обрабатывает внешние стимулы, вынуждая внешний мир коллапсировать из предыдущего режима ?чистого состояния? приостановленного оживления в систему собственных функций или ?категорий?. Характеристики зтой познавательной системы зависят от используемого оператора и иерархического уровня, на котором происходит абстрагирование. В зтой статье мы моделируем физику такого познавательного процесса. Обсуждается синтез марковских процессов, происходящий внутри отдельного злемента ?атрактор-память?, и марковский или полумарковский процесс, включающий пережежающиеся прыжки между различными злементами ?атракторпамять?.

     

Individual and group dynamics in purchasing activity

As a major part of the daily operation in an enterprise, purchasing frequency is in constant change. Recent approaches on the human dynamics can provide some new insights into the economic behavior of companies in the supply chain. This paper captures the attributes of creation times of purchase orders to an individual vendor, as well as to all vendors, and further investigates whether they have some kind of dynamics by applying logarithmic binning to the construction of distribution plots. It’s found that the former displays a power-law distribution with approximate exponent 2.0, while the latter is fitted by a mixture distribution with both power-law and exponential characteristics. Obviously, two distinctive characteristics are presented for the interval time distribution from the perspective of individual dynamics and group dynamics. Actually, this mixing feature can be attributed to the fitting deviations as they are negligible for individual dynamics, but those of different vendors are cumulated and then lead to an exponential factor for group dynamics. To better describe the mechanism generating the heterogeneity of the purchase order assignment process from the objective company to all its vendors, a model driven by product life cycle is introduced, and then the analytical distribution and the simulation result are obtained, which are in good agreement with the empirical data.     

The effects of nonlinear interactions and network structure in small group opinion dynamics

We present a model of opinion dynamics in social networks in which an individual's opinion evolves under the action of (i) a linear force which tends to restore the opinion back towards the individual's natural bias that is his or her initial opinion and (ii) a nonlinear coupling with other individuals which acts to bring opinions closer together but wanes for high opinion discrepancies. Bifurcation analysis for the case of a two-person group shows that a critical value for the difference in natural biases exists which demarcates regimes of qualitatively different behavior. For low to moderate natural bias differences, the dynamics are qualitatively similar to linear theory. For high bias differences, the system takes on a binary nature and is marked by discontinuous transitions between deadlock and consensus as well as hysteresis as the coupling is varied. The coupling required to force consensus grows extremely rapidly with the natural bias difference indicating that trying to achieve group consensus solely via increasing the communications rate becomes fruitless as the biases become extremely divergent. We also show that, for high bias differences, a triad broker network topology can reduce group discord more effectively than a clique, contrary to linear theory.     

Human dynamic model co-driven by interest and social identity in the MicroBlog community

This paper analyzes the behavior of releasing messages in the MicroBlog community and presents a human dynamic model co-driven by interest and social identity. According to the empirical analysis and simulation results, the messaging interval distribution follows a power law, which is mainly influenced by the degree of users’ interests. Meanwhile, social identity plays a significant role regarding the change of interests and may slow down the decline of the latter. A positive correlation between social identity and numbers of comments or forwarding of messages is illustrated. Besides, the analysis of data for each 24 h reveals obvious differences between micro-blogging and website visits, email, instant communication, and the use of mobile phones, reflecting how people use small amounts of time via mobile Internet technology.     

Graph kernels,hierarchical clustering,and network community structure: experiments and comparative analysis

There has been a quickly growing interest in properties of complex networks, such as the small world property, power-law degree distribution, network transitivity, and community structure, which seem to be common to many real world networks. In this study, we consider the community property which is also found in many real networks. Based on the diffusion kernels of networks, a hierarchical clustering approach is proposed to uncover the community structure of different extent of complex networks. We test the method on some networks with known community structures and find that it can detect significant community structure in these networks. Comparison with related methods shows the effectiveness of the method.     

Quantum information processing and metrology with color centers in diamonds

The Nitrogen Vacancy （NV） center is becoming a promising qubit for quantum information processing. The defect has a long coherence time at room temperature and it allows spin state initialized and read out by laser and manipulated by microwave pulses. It has been utilized as a ultra sensi- tive probe for magnetic fields and remote spins as well. Here, we review the recent progresses in experimental demonstrations based on NV centers. We first introduce our work on implementation of the Deutsch- Jozsa algorithm with a single electronic spin in diamond. Then the quantum nature of the bath around the center spin is revealed and continuous wave dynamical decoupling has been demonstrated. By applying dynamical decoupling, a multi-pass quantum metrology protocol is realized to enhance phase estimation. In the final, we demonstrated NV center can be regarded as a ultra-sensitive sensor spin to implement nuclear magnetic resonance （NMR） imaging at nanoscale.     

Opinion dynamics in networked command and control organizations

An opinion dynamics model for a Command and Control (C2) organization is essential for simulating combat system effectiveness. However, few studies have addressed opinion evolution in C2 simulation. With the goal of overcoming this research gap, this paper proposes an opinion exchange model, which is illustrated through a practical example of an Armored Division network. The model is divided into homogeneous and heterogeneous aspects: the former is mainly characterized by communication rules and types, while the latter is extended with the influence of multi-level opinion leaders. After carrying out the simulation of the two main models, the results show that the opinion evolution of the hierarchical leveled C2 organization with descending influence is much more complex and unpredictable than that of social networks.     

Determination of Lamb–Mössbauer factors and lattice dynamics in some nitroprusside single crystals

Mössbauer spectra have been recorded for sodium, guanidinium, barium and lithium nitroprussides single crystal cuts. The temperature dependence of the Lamb–Mössbauer fraction f, respectively, the mean-square nuclear displacement 〈x ²〉 and the mean-square (of the total) velocity of the iron nucleus 〈v ²〉 were analyzed on the basis of the Debye and Einstein lattice-vibration models. The characteristic temperatures of the two models, θ _D and θ _E, fitted to 〈x ²〉 are considerably lower than those fitted to 〈v ²〉. This effect seems to be typical for the iron complexes and was explained with the presence of low and high frequencies in the phonon vibration spectra and of low-temperature anharmonicity. The Lamb–Mössbauer fraction at 77 K in all principal crystal directions of sodium, guanidinium and barium nitroprussides has been determined. These values will be used for more precise studies of the population and the properties of the light-induced molecular states of the nitrosyl [Fe(CN)₅NO]^2? anion.     

Transnational networks,diffusion dynamics,and electoral revolutions in the postcommunist world

Since 1996, eight elections have taken place in postcommunist Europe and Eurasia that have replaced illiberal with liberal governments. There is ample evidence that these “electoral revolutions” reflected the cross-national diffusion of a distinctive model of regime change that was developed elsewhere and that was designed to promote democratization in authoritarian political contexts featuring semi-competitive elections. This electoral model spread throughout the postcommunist region because of both shared perceptions by opposition groups of similar local conditions and the existence of transnational democracy promotion networks that included local, regional and American participants. As these revolutions spread, however, they were less successful in carrying through democratic change-in part because local conditions were less supportive and in part because authoritarian leaders and their international allies were both forewarned and forearmed.     

Homogeneous nucleation and growth in iron-platinum vapour investigated by molecular dynamics simulation

Homogeneous nucleation and growth from binary metal vapour is investigated by molecular dynamics simulation. It is focused here mainly on the iron-platinum system with a mole fraction of 0.5. The simulations are started in the highly supersaturated vapour phase. Argon is added as carrier gas removing the heat of condensation from the forming clusters. The embedded atom method is employed for modelling of the force field of iron and platinum. The simulation runs are evaluated with respect to the nucleation rate, monomer temperature, monomer amount, and with respect to the size of the largest cluster in the system including possible pure metal clusters. It turns out that depending on the composition of the complete system pure platinum clusters with sizes up to 10 to 15 atoms are formed in addition to binary clusters. Due to the high temperature of these clusters iron atoms less likely condense at the beginning of the particle formation simulation. This leads to temporary difference in the temperatures of the platinum and the iron subsystems, which eventually approach each other when only binary clusters are present. In summary, the results obtained from the cluster statistics show that pure platinum nucleation and growth can take place to some extent within the binary system.     

Random field Ising model and community structure in complex networks

We propose a method to determine the community structure of a complex network. In this method the ground state problem of a ferromagnetic random field Ising model is considered on the network with the magnetic field B_s = +∞, B_t = -∞, and B_i≠s,t=0 for a node pair s and t. The ground state problem is equivalent to the so-called maximum flow problem, which can be solved exactly numerically with the help of a combinatorial optimization algorithm. The community structure is then identified from the ground state Ising spin domains for all pairs of s and t. Our method provides a criterion for the existence of the community structure, and is applicable equally well to unweighted and weighted networks. We demonstrate the performance of the method by applying it to the Barabási-Albert network, Zachary karate club network, the scientific collaboration network, and the stock price correlation network. (Ising, Potts, etc.)     

Compromise and synchronization in opinion dynamics

We discuss two models of opinion dynamics. We first present a brief review of the Hegselmann and Krause (HK) compromise model in two dimensions, showing that it is possible to simulate the dynamics in the limit of an infinite number of agents by solving numerically a rate equation for a continuum distribution of opinions. Then, we discuss the Opinion Changing Rate (OCR) model, which allows to study under which conditions a group of agents with a different natural tendency (rate) to change opinion can find the agreement. In the context of the this model, consensus is viewed as a synchronization process.     

Butterfly interconnection networks and their applications in Walsh-Hadamard transform-based information processing and optical computing

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Braid theory and Zipf-Mandelbrot relation used in microparticle dynamics

A study is presented of the dynamics of a few body system of microparticles by using rank-ordering statistics in order to gain insight in the magneto-rheological properties of ferrofluids. This dynamical system is made up of micrometer sized plastic spheres dispersed in a ferrofluid driven by external magnetic fields. The world lines of the microspheres are captured and the dynamical modes are described by mathematical braid theory. Rank-ordering statistics on these modes shows a wide power law region consistent with the Zipf-Mandelbrot relation. We have also performed numerical simulations of the experimental system which show results in agreement with the observations.