离散时间多智能体系统一致性的平均驻留时间条件

研究高阶离散时间线性多智能体系统在有向切换信息拓扑下的状态一致性问题。首先通过提出的线性变换将该一致性问题转换为相应离散时间线性切换系统的渐近稳定性问题。然后借助于切换系统稳定性的平均驻留时间方法,分别得到如下两种情形下该一致性问题可解的充分条件：1)信息拓扑集合中的一部分拓扑是可一致的;2)信息拓扑集合中所有信息拓扑是可一致的。最后通过数值仿真验证了所得理论结果的正确性。     

具有双重认知能力的人工蜂群算法及性能分析

针对人工蜂群算法在解决单峰问题时收敛速度过慢而在优化多峰问题时易陷入局部最优值的问题,依据群体动力学原理,引入"自我认知能力"和"社会认知能力"对蜂群觅食时的蜜源搜索策略进行改进,提出了具有双重认知策略的人工蜂群算法。用经典的标准测试函数进行了实验并与其他改进算法进行了比较,结果表明,改进的搜索策略提高了算法的优化能力,优于其他改进的人工蜂群算法。     

An extension of the group contribution method for estimating thermodynamic and transport properties part II. Polyatomic gases (F2, Cl2, CS2, H2S, NO and N2O)

Earlier work on the group contribution method applied to the Kihara potential is extended to polyatomic gases for the calculation of second virial coefficients, viscosities and diffusivities of dilute gases with a single set of gas group parameters. Functional group parameters are evaluated from the simultaneous regression of second virial coefficient and viscosity data of pure gases. Parameters for gas groups (F₂, Cl₂, CS₂, H₂S, NO, nd N₂O) are found to provide good predictions of second virial cross coefficients, mixture viscosities and binary diffusion coefficients of gas-gas mixtures. Application of the model shows that second virial coefficient data can be represented with good results comparable to the values by means of the corresponding states model. The reliability of the present model in viscosity predictions is proved by comparison with the Lucas method. Predictions of binary diffusion coefficients are in excellent agreement with experimental data and compare well with values obtained by means of the Fuller method.     

Design of output feedback consensus controllers for nonlinear sampled-data multi-agent systems of strict-feedback form

Design of reduced-order observer-based output feedback consensus controllers for nonlinear sampled-data multi-agent systems of strict-feedback form is considered based on nonlinear sampled-data control and consensus control theories. As a practical application of the proposed design method, output feedback consensus control for sampled-data fully actuated ships is also discussed.     

Exploring students' learning effectiveness and attitude in Group Scribbles‐supported collaborative reading activities: a study in the primary classroom

Improving students' reading comprehension is of significance. In this study, collaborative learning supported by Group Scribbles (GS), a networked technology, was integrated into a primary reading class. Forty‐seven 10‐year‐old students from two 4th grade classes participated in the study. Experimental and control groups were established to investigate the effectiveness of GS‐supported collaborative learning in enhancing students' reading comprehension. The results affirmed the effectiveness of the intervention designed. In the experiment group, students' learning attitudes, motivation and interest were enhanced as well. Further analyses were done to probe students' interaction processes in the networked collaborative classroom and different collaboration patterns and behaviours were identified. Based on the findings obtained, implications for future learning design to empower L1 learning were elaborated.     

线性多智能体系统一致性问题的部分稳定性方法

提出了处理高阶线性多智能体系统一致性问题的线性变换.该线性变换将一致性问题转化为一个部分稳定问题.研究了一般线性协议下线性多智能体系统的三个问题: 1) 寻找一致性收敛判据; 2) 计算一致性函数; 3) 设计线性一致性协议的增益矩阵.具体来说,提出了基于矩阵 Hurwitz 稳定的一致性收敛的充分必要条件,给出了一致性函数的解析表达式,同时建立了一致性协议的增益矩阵与多智能体系统收敛时间和一致性精度的关系,并针对预先给定的收敛时间和精度要求设计了增益矩阵.     

复杂分数阶多自主体系统的运动一致性

复杂环境中,许多自然现象的动力学特性不能应用整数阶方程描述,而只能用分数阶（非整数阶）动力学的智能个体合作行为来解释. 本文假设多自主体 系统存在个体差异,采用不同的分数阶动力学特性组成复杂分数混合阶微分方程. 应用分数阶系统的Laplace变换和频域理论,研究了有向网络拓扑下,时延分数混合阶多自主体系统的运动一致性. 由于整数阶系统是分数阶系统的特殊情况,本文的结论可以推广到整数阶与分数阶混合的多自主体系统中. 最后,应用仿真实例对本文结论进行了验证.     

Synthesis, characterization and evaluation of amphiphilic diblock copolymer emulsifiers based on methoxy hexa(ethylene glycol) methacrylate and benzyl methacrylate

Linear, amphiphilic diblock copolymers based on the nonionic, hydrophilic monomer methoxy hexa(ethylene glycol) methacrylate (HEGMA) and the hydrophobic monomer benzyl methacrylate (BzMA) of different molecular weights and compositions were synthesized by group transfer polymerization. The molecular weights and comonomer compositions of these copolymers were characterized by gel permeation chromatography and proton nuclear magnetic resonance (¹H NMR) spectroscopy, respectively. Dynamic light scattering on aqueous solutions of the diblock copolymers indicated that all the copolymers formed aggregates whose size increased with the % w/w BzMA composition and with the overall molecular weight of the linear chains. Turbidimetry on 1% w/w aqueous copolymer solutions was used to determine the cloud points, which were found to increase with the composition in hydrophilic units and the linear chain molecular weight. After polymer characterization, xylene/water and diazinon (pesticide)/water emulsions were prepared using the above polymers as stabilizers at 1% w/w polymer concentration and at different overall organic phase/water ratios. At an organic phase/water mass ratio of 4/1, the lower molecular weight (2500 and 5000 g mol⁻¹) diblock copolymers provided stable single-phase o/w emulsions, matching the behavior of commercially available hydrophilic Pluronics.     

UNIFAC基团贡献法估算甲醇-碳酸二甲酯的汽液相平衡

以甲醇-碳酸二甲酯为实验物系，在考虑了汽、液混合物非理想性的情况下，用UNIFAC基团贡献法估算了液相活度系数，用维里方程求算了汽相逸度系数。并最终给出了此二元物系在不同压力下的汽液相平衡数据，结果表明其共沸组成(甲醇摩尔分数)随压力的增高而增大，当压力从0．1MPa增至1．5MPa时，共沸组成由0．890增加到0．960。最后将常压下的相平衡数据与实验值进行了对比，二者的最大偏差为9．4％。