Emulation and complementarity in one‐dimensional alternatives of the axelrod model with binary features

We investigate the one‐dimensional dynamics of alternatives of the Axelrod model (ξ_t) with k binary features and confidence parameter ε = 0, 1,…, k. Simultaneously, the simple Axelrod model is also critically examined. Specifically, for small and large ε, simulations suggest that the convergent model (ξ_t) is emulated by a corresponding attractive model (η_t) with the same parameters (conditional on bounded confidence). (η_t) is more mathematically tractable than (ξ_t), and the very definitions of the two qualitative behaviors of cyclic particle systems (fluctuation and fixation) are applicable in special cases. Moreover, we observe a complementarity: for not too small k and $\varepsilon \approx {k \over 2}$ , (η_t) fixates (each site has a final type independent of the possibly infinite size of the lattice), whereas (ξ_t) fluctuates (each site changes type at arbitrarily larger times t as the size of the lattice increases). © 2011 Wiley Periodicals, Inc. Complexity, 2011     

Self‐organizing traffic lights at multiple‐street intersections

The elementary cellular automaton following rule 184 can mimic particles flowing in one direction at a constant speed. Therefore, this automaton can model highway traffic qualitatively. In a recent paper, we have incorporated intersections regulated by traffic lights to this model using exclusively elementary cellular automata. In such a paper, however, we only explored a rectangular grid. We now extend our model to more complex scenarios using an hexagonal grid. This extension shows first that our model can readily incorporate multiple‐way intersections and hence simulate complex scenarios. In addition, the current extension allows us to study and evaluate the behavior of two different kinds of traffic‐light controller for a grid of six‐way streets allowing for either two‐ or three‐street intersections: a traffic light that tries to adapt to the amount of traffic (which results in self‐organizing traffic lights) and a system of synchronized traffic lights with coordinated rigid periods (sometimes called the “green‐wave” method). We observe a tradeoff between system capacity and topological complexity. The green‐wave method is unable to cope with the complexity of a higher‐capacity scenario, while the self‐organizing method is scalable, adapting to the complexity of a scenario and exploiting its maximum capacity. Additionally, in this article, we propose a benchmark, independent of methods and models, to measure the performance of a traffic‐light controller comparing it against a theoretical optimum. © 2011 Wiley Periodicals, Inc. Complexity, 2012     

Detonability of THDCPD-exo–air mixtures

In the frame of industrial risk and propulsive application, the detonability study of JP10–air mixtures was performed. The simulation and measurements of detonation parameters were performed for THDCPD-exo/air mixtures at various initial pressure (1 bar < P ₀ < 3 bar) and equivalence ratio (0.8 < Φ < 1.6) in a heated tube (T ₀ ~ 375 K). Numerical simulations of the detonation were performed with the STANJAN code and a detailed kinetic scheme of the combustion of THDCPD. The experimental study deals with the measurements of detonation velocity and cell size λ. The measured velocity is in a good agreement with the calculated theoretical values. The cell size measurements show a minimum value for Φ ~ 1.2 at every level of initial pressure studied and the calculated induction length L _i corresponds to cell size value with a coefficient k = λ/L _i = 24 at P ₀ = 1 bar. Based on the comparison between the results obtained during this study and those available in the literature on the critical initiation energy E _c, critical tube diameter d _c and deflagration to detonation transition length L _DDT, we can conclude that the detonability of THDCPD–air mixtures corresponds to that of hydrocarbon–air mixtures.

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This paper is based on the work presented at the 33rd International Pyrotechnics Seminar, IPS 2006, Fort Collins, July 16–21, 2006.     

Station Model for Rail Transit System Using Cellular Automata

In this paper, we propose a new cellular automata model to simulate the railway traffic at station. Based on NaSch model, the proposed station model is composed of the main track and the siding track. Two different schemes for trains passing through station are considered. One is the scheme of ＂pass by the main track, start and stop by the siding track＂. The other is the scheme of ＂two tracks play the same role＂. We simulate the train movement using the proposed model and analyze the traffic flow at station. The simulation results demonstrate that the proposed cellular automata model can be successfully used for the simulations of railway traffic. Some characteristic behaviors of railway traffic flow can be reproduced. Moreover, the simulation values of the minimum headway are close to the theoretical values. This result demonstrates the dependability and availability of the proposed model.     

Cellular Automata Models of Traffic Behavior in Presence of SpeedBreaking Structures

In this article, we study traffic flow in the presence ofspeed breaking structures. The speed breakers are typically used toreduce the local speed of vehicles near certain institutions such asschools and hospitals. Through a cellular automata model we study the impact of such structures on global traffic characteristics. The simulation results indicate that the presence of speed breakers could reduce the global flow under moderate global densities. However, under low and high global density traffic regime the presence of speed breakers does not have an impact on the global flow. Further the speed limit enforced by the speed breaker createsa phase distinction. For a given global density and slowdown probability, as the speed limit enforced by the speed breaker increases, the traffic moves from the reduced flow phase to maximum flow phase. This underlines the importance of proper design of these structures to avoid undesired flow restrictions.     

微流控芯片中细胞动态胞吞二氧化硅纳米颗粒的研究

研究了用微流控芯片在体外模拟人体血液流动状态下细胞胞吞二氧化硅纳米粒子的方法和特性. 通过调节储液池的液面差, 使细胞从微通道入口流入并在通道内沉积贴壁生长. 将含有贴壁细胞的微流控芯片放入37 ℃/体积分数5%CO₂的培养箱中, 使细胞培养液连续流过贴壁细胞. 培养24 h后, 在流动的培养液中加入作为荧光标记物的500 nm 粒径的掺杂有异硫氰酸荧光素(FITC)的二氧化硅微球(MSN), 继续培养6 h后, 用荧光显微镜测定细胞胞吞二氧化硅纳米粒子后的荧光强度, 考察了不同流速下细胞对二氧化硅微球摄入量的影响. 结果表明, 在动态条件下, 细胞对二氧化硅微球的吞噬量明显下降, 当流速从0.022 mm/s 增加至0.74 mm/s时, 吞噬量从静态测得值的74.7%下降至7.1%.     

乙二醛诱导细胞凋亡的近红外表面增强拉曼光谱

将60 nm金纳米粒子导入到活的人骨肉瘤细胞中, 用近红外表面增强拉曼散射(SERS)技术获取细胞内化学成分的高分辨SERS信息. 对正常活性细胞和乙二醛诱导的凋亡细胞的比较研究表明, 对于正常活性的细胞, 金纳米探针主要分布在细胞质内(围绕细胞核), 而凋亡细胞内的金纳米探针的分布较为均匀, 在遍布凋亡细胞内的各个位置包括细胞表面均容易找到DNA片段的信息.     

Zwitterionic Mixed Valence: Internalizing Counteranions into a Biferrocenium Framework toward Molecular Expression of Half-Cells in Quantum Cellular Automata

Realization of molecular quantum cellular automata (QCA), a promising architecture for molecular computing through current-free processes, requires improved understanding and application of mixed-valence (MV) molecules. In this report, we present an electrostatic approach to creating MV subspecies through internalizing opposite charges in close proximity to MV ionic moieties. This approach is demonstrated by unsymmetrically attaching a charge-responsive boron substituent to a well-known organometallic MV complex, biferrocenium. Guest anions (CN⁻ and F⁻) bind to the Lewis acidic boron center, leading to unusual blue-shifts of the intervalence charge-transfer (IVCT) bands. To the best of our knowledge, this is the first reported example of a zwitterionic MV series in which the degree of positive charge delocalization can be varied by changing the bound anions, and serves to clarify the interplay between IVCT parameters. The key underlying factor is the variable zero-level energy difference in the MV states. This work provides new insight into imbuing MV molecules with external charge-responsiveness, a prerequisite of molecular QCA techniques.     

A Tetrairon Dication Featuring Tetraethynylbenzene Bridging Ligand: A Molecular Prototype of Quantum Dot Cellular Automata

The unprecedented tetrairon dication [{Cp*(dppe)FeC≡C-}₄-μ-(1,2,4,5-C₆H₂)](PF₆)₂ ( 1 ) was obtained through a sequence of three reactions from 1,2,4,5-tetraethynylbenzene, Cp*(dppe)FeCl (Cp*=C₅Me₅, dppe=1,2-bis(diphenylphosphino)-ethane), KOtBu, and ferrocenium hexafluorophosphate. The cyclic voltammogram of the target molecule, isolated in 77 % yield, exhibits four well separated and reversible redox events showing that 1 is thermodynamically stable with respect to disproportionation (Kc>10⁶). The tetranuclear dication 1 was characterized by XRD on single crystal, IR and NMR spectroscopies and Mössbauer spectrometry. The experimental data show that 1 behaves as a class II mixed-valence complex with the positive charges preferentially disposed on antipodal positions. This new molecule can be regarded as a potential molecular prototype of quantum dot cellular automata.