具有不同时延的多智能体系统一致性分析

针对有向加权且存在全局可达点的静态网络拓扑, 考虑了同时具有通信时延和输入时延的一阶、二阶智能体系统的运动一致性问题. 基于广义Nyquist准则与频域控制理论的方法, 分析并得到了网络中所有智能体渐进收敛到一致状态的充分条件. 通过该条件发现一致性的达到只与系统的耦合强度、智能体的输入时延以及各自的连接状态信息有关, 与通信时延无关. 但是, 通信时延的存在却要影响系统的动态特性. 仿真实验结果进一步验证了理论分析所得结论的正确性.     

一种热集成系统的动态多智能体微分进化算法

针对热集成系统换热网络存在的严重非凸非线性与多维多极值问题,提出动态多智能体微分进化算法.结合动态更新策略,并引入多智能体算法的环境感知能力,改进微分进化算法的种群生成方式与变异机制,并增强在大规模复杂非线性系统中的全局搜索能力.通过10SP2与9SP1换热网络经典算例优化,得到最佳年综合费用,体现出了改进算法更优的全局搜索能力.     

纳米接触行为的三维多尺度数值模拟

应用分子动力学与有限元耦合的桥域多尺度算法,模拟三维刚性球形压头与光滑基体表面的纳米尺度接触行为,并与全原子分子模拟结果比较.考察在一定载荷下的系统弛豫行为、两种模型桥接区位移和应力的连续性、法向力和接触面积随压头位移变化等,结果表明:一定外载荷下,桥域多尺度算法能较快达到平衡状态,且压头的振荡幅度更小,系统初始温度为0 K时该算法的相对误差最小.在准静态加载过程中,该算法能够将原子区的位移、应力等连续的过渡到连续介质区,具有较好的耦合效果;法向力-压头位移和接触半径-压头位移曲线几乎与分子模拟结果重合,表明算法具有较高的计算精度.     

领导-跟随多智能体系统的滞后一致性

近年来,随着应用的需要和技术的发展,多智能体系统的一致性逐渐成为研究热点.在通信网络和工程应用中,由于信号传播的延迟效应,系统中智能体的状态可能表现为滞后一致.本文提出多智能体系统的滞后一致性概念,研究了有向网络环境下一阶领导-跟随多智能体系统的滞后一致性问题.通过设计合适的控制协议,利用矩阵理论和稳定性理论,获得该系统达到滞后一致的充分条件.数值模拟验证了理论结果的正确性.     

时延多智能体系统分组一致性分析

研究了拓扑结构为连通无向图与连通二分图的一阶时延多智能系统分别在两类控制协议下的分组一致性问题．基于广义Nyquist准则与频域控制理论的方法,分析并得到了多智能体系统渐进分组收敛一致的充分条件．通过该条件发现系统分组一致性的达到与系统的时延以及智能体间的耦合强度相关．同时,时延的大小影响着系统的收敛速度与动态性能．仿真实验的结果进一步验证了理论分析所得结论的正确性．     

离散异质多智能体系统的分组一致性控制

针对一类混合异质多智能体系统的分组一致性控制问题进行了研究。具体分析了由一阶智能体和二阶智能体组成的混合异质系统,研究其在离散情况下的分组一致性。基于两个合理的假设提出了线性控制协议,运用代数图论、稳定性理论和矩阵理论,分析协议作用下闭环系统的系统矩阵及动态特性,取得了系统渐近实现分组一致性的充分条件,该条件与系统拓扑结构、采样周期以及控制参数有关。结论同时适用于有向拓扑与无向拓扑,最后通过仿真实例对所得分析结果进行了验证。     

相变蓄热蜂窝体传热行为数值模拟研究

高温空气燃烧技术通过回收烟气余热降低燃料消耗而得到了广泛应用,换向时间对燃烧特性有重要影响,并与蓄热体结构和材料种类有关。本文建立了含金属类相变蓄热复合蜂窝体蓄/放热模型,考虑材料热物性随温度变化和热辐射,对蜂窝体的蓄/放热过程进行数值模拟,研究了相变材料和换向时间对空气预热温度、能量回收率的影响。计算结果表明,换向时间为120s时,含相变材料的蜂窝体比普通蜂窝体的空气预热温度高39.52 K;从放热开始到结束,含相变材料的蜂窝体的空气预热温度下降幅度约为普通蜂窝体的1/2;使用含相变材料的蜂窝体将换向时间从60 s有效延长至120 s时,空气预热温度高于换向时间未延长的普通蜂窝体,并且保持较高的能量回收率。     

链式多智能体遗传算法在分布式电源全时序上优化配置

分布式电源的选址与定容是微电网研究所面临的重要问题,本文主要考虑规划地区的24-h负荷时序特性和气候特点的24-h负荷变换的情况下的DG优化配置。针对以上问题,通过链式多智能体遗传算法对其进行优化处理。首先通过算法对IEEE33节点系统进行测试,验证算法在分布式电源优化配置中的优越性,并对PG E69节点配电网进行24-h时序的全过程模拟仿真优化,结果验证了多智能体遗传算法能在分布式电源配置上的有效性,同时提高微电网接入的预测精度,加快收敛速度,改进陷入局部最优的可能性等问题,对微电网在规划选址与定容选择上提供工程参考的实用性。     

多智能体系统的队形控制方法及应用综述

多智能体系统队形控制的研究主要集中于队形形成、队形保持和队形变换三个方面。首先,介绍、分析了多种队形控制方法,包括轨迹跟踪法、行动选择法、假想刚体法、网络关系图分析法、动态编队法、虚拟势场法、学习控制法和混合控制法等;其次,对移动机器人、无人机、水下机器人等多智能体系统的队形控制应用进行研究;然后,给出了近年来多智能体系统队形控制的研究进展,包括基于复Laplacian矩阵的多维空间队形控制方法,其它领域技术(云计算、图像处理等)用于队形控制的研究成果,并对基于队形控制的多移动机器人和无人机搬运作了介绍;最后,给出了当前队形控制研究中尚未解决的问题,包括队形扩展,队形稳定性,通信、传感器功能,异构多智能体系统队形控制和机械臂编队等。     

随机相互作用下多体系统的规则结构

讨论随机相互作用下的多体系统规则结构方面研究的主要结果, 着重讨论自旋为零占主导地位的理论研究现状, 能量中心的性质, 集体性等, 举例说明这一领域的研究方法、意义和前景.     

Multi-agent coordination in directed moving neighbourhood random networks

This paper considers the consensus problem of dynamical multiple agents that communicate via a directed moving neighbourhood random network.Each agent performs random walk on a weighted directed network.Agents interact with each other through random unidirectional information flow when they coincide in the underlying network at a given instant.For such a framework,we present sufficient conditions for almost sure asymptotic consensus.Numerical examples are taken to show the effectiveness of the obtained results.     

Pedestrian choice behavior analysis and simulation of vertical walking facilities in transfer station

Considering the interlayer height, luggage, the difference between queuing pedestrians, and walking speed, the pedestrian choice model of vertical walking facilities is established based on a support vector machine. This model is verified with the pedestrian flow data of Changchun light-rail transfer station and Beijing Xizhimen transfer station. Adding the pedestrian choice model of vertical walking facilities into the pedestrian simulation model which is based on cellular automata, the pedestrian choice behavior is simulated. In the simulation, the effects of the dynamic influence factors are analyzed. To reduce the conflicts between pedestrians in opposite directions, the layout of vertical walking facilities is improved. The simulations indicate that the improved layout of vertical walking facilities can improve the efficiency of pedestrians passing.     

Effect of temperature on crystalline silicon solar cells processed from chemical and metallurgical route

Effect of temperature on monocrystalline and multicrystalline silicon solar cells processed from chemical (EG-Si) and metallurgical (SoG_M-Si) routes was investigated in the range of 280–350 K. The temperature coefficients of important parameters related with the cell property were discussed. Experimental results indicate that the T-coefficient of conversion efficiency (η) of multicrystalline EG-Si cell processed from chemical is only 68% that of the monocrystalline EG-Si cell. Furthermore, the η of both types of SoG_M-Si cells decrease much less than that of the EG-Si cells with the increase in temperature. Additionally, the recombination fraction, the minority carrier lifetime, the carrier mobility decrease and the band-gap shrinkage were also investigated to reveal the intrinsic temperature dependence mechanism. In order to confirm the results, we used numerical simulation software AMPS-1D (analysis of microelectronic and photonic structure in one dimension program) to simulate the temperature dependence of solar cell performances. The results of numerical simulation were basically consistent with the experimental results.     

网络交通流动态演化的混沌现象及其控制

本文以含2条平行路径的交通网络为例, 探讨了网络交通流逐日动态演化问题. 首先, 建立了动态系统模型来刻画网络交通流的演化过程, 动态系统模型的不动点就是随机用户平衡解, 证明了平衡解存在且唯一. 然后, 根据非线性动力学理论, 推导出了网络交通流演化的稳定性条件. 其次, 通过数值实验, 分析了网络交通流的演化特征, 发现了在一定条件下流量的周期振荡和混沌现象. 最后, 以OD需求为控制变量推导出了网络交通流混沌控制的方法.     

Application of stochastic computer simulation to a solution of a nonlinear Fokker-Planck equation governing bacteria chemotaxis

A stochastic computer simulation technique has been used to solve a one-dimensional time-dependent Fokker-Planck (F-P) equation governing spacetime distribution of bacteria in a substrate (food) gradient. Because of consumption of the substrate by the bacteria the F-P equation becomes nonlinear due to coupling of the distribution with the self-generated substrate gradient. The simulation is efficient and numerically accurate for generating transient solutions. We are able not only to produce a transient solution displaying approach to the steady state solitary wave solution known from an analytical result of Keller and Segal but also to show an interesting dependence of the solitary wave propagation speed on the concentration dependence of the substrate consumption rate.     

Stochastic simulation of fermions

Journal of Statistical Physics -     

Stochastic simulation of variations in the autoignition delay time of premixed methane and air

A mesoscopic stochastic particle model for homogeneous combustion is introduced. The model can be used to investigate the physical fluctuations in a system of coupled chemical reactions with energy (heat) release/consumption. In the mesoscopic model, the size of the homogeneous gas volume is an additional variable, which is eliminated in macroscopic continuum models by the thermodynamic limit N→∞. Thus, continuous homogeneous models are macroscopic models wherein fluctuations are excluded by definition. Fluctuations are known to be of particular importance for systems close to the autoignition limits. The new model is used to investigate the stochastic properties of the autoignition delay time in a homogeneous system with stoichiometric premixed methane and air. Temperature and species concentrations during autoignition of sub-macroscopic volumes, including physically meaningful fluctuations, are presented. It is found that different realizations mainly differ in the time when ignition occurs; besides this the development is similar. The mesoscopic range and the macroscopic limit are identified. Which range a specific system is assigned to is not only a question of the length scale or particle number, but also depends on the complete thermodynamic state. The stochastic algorithm yields the correct results for the macroscopic limit compared to the continuous balance equations. The sensitivity of the results to two different detailed reaction mechanisms (for the same system) is studied and found to be low. We show that when approaching the autoignition limit by decreasing the temperature, the fluctuations in the autoignition delay time increase and an increasing number of realizations will have exceedingly long ignition delay times, meaning they are in practice not autoignitable. With this result the mesoscopic simulations offer an explanation of the transition between autoignitable and non-autoignitable conditions. The calculated distributions were compared with ten repetitions of the same experiment. A mesoscopic distribution that matches the experimental results was found.     

Analogue simulation of quantum mechanical systems

An extension of the technique of analogue simulation to the treatment of quantum mechanical systems, based on an analogue variant of the method of stochastic quantization, is reported. The analogue stochastic quantization (ASQ) technique is introduced by application to the quantum harmonic oscillator, a particularly simple system for which all the answers are already known. ASQ measurements of the lowest eigenvalues and eigenfunctions of the latter system are presented and compared with theoretical predictions. The future potential of the ASQ technique in relation to some more complicated quantum systems of topical interest is discussed.     

Cu-Au体系非对称异质外延行为的分子动力学研究

利用分子动力学模拟方法研究了Cu/Au(001)和Au/Cu(001)异质外延岛的演化行为. 研究结果显示：Cu-Au体系的相互外延行为呈现出明显的非对称性. Cu在Au(001)基体表面可以形成完整的外延结构，而Au在Cu(001)基体表面外延将导致失配位错的出现. 导致非对称外延生长行为的根本原因是外延岛的应变状态的差异和外延岛自身性质的不同. 随着外延岛的长大，Cu外延岛与Au(001)基体的微观失配度由最初的接近宏观失配度的9%左右迅速单调下降，并最终趋于晶格匹配；而Au在Cu(001)基体表面外延的微观失配度则呈现出振荡增加趋势. Cu/Au(001)体系的基体形变主要发生在外延岛的边缘，而Au/Cu(001)体系的基体形变主要发生在外延岛内部所对应的区域.