Exponential synchronization of complex dynamical networks with markovian jump parameters and stochastic delays and its application to multi-agent systems

This paper studies the synchronization problem of complex dynamical networks with stochastic delay which switches stochastically among several forms of time-varying delays. Both the discrete and distributed delays are considered, as well as the Markovian jump parameters. The occurrence probability distribution of the stochastic delay is assumed to be known in prior. By utilizing the Lyapunov–Krasovskii stability theory and stochastic analysis techniques, some sufficient exponential synchronization criteria are obtained, which depend not only on the size of delays, but also on the occurrence probability distribution of the stochastic delay. Moreover, the main results are successfully extended to multi-agent systems with stochastic delay. Several numerical examples are given to illustrate the feasibility and effectiveness of the proposed methods.     

Effect of Annealing Poly(4-Methylpentene) and of Oxidative Degradation during Annealing

Injection molded specimens of a poly(4-methylpentene) (TPX) were annealed at temperatures between 140 and 220°C for times up to 500 min in air, and the annealed TPX specimens were characterized by the differential scanning calorimeter, UV–visible spectrometry, FT-IR, and X-ray diffraction. The annealing of the TPX specimens at 140–180°C for 50 min showed little effect on their thermal properties. However, the thermal properties were significantly affected by annealing at 200–220°C, and the change was dependent on the annealing time. Besides the annealing effect, the thermal properties were also affected by oxidative degradation. Severe oxidative degradation can destroy the crystalline structure and thus decreases the crystallinity. The oxidative degradation phenomenon of the TPX specimens during annealing can be simulated by isothermal scanning of the weight loss in air by thermal gravimetric analysis.     

季铵盐型Gemini表面活性剂在金表面的吸附行为

以邻苯二酚(CC)为电化学探针, 利用循环伏安、交流阻抗等方法研究了不同阳离子Gemini表面活性剂(C16H33(CH3)2N-C4H8-N(CH3)2C16H33 (C16-C4-C16)、C12H25(CH3)2N-C4H8-N(CH3)2C12H25 (C12-C4-C12)、C8H17(CH3)2N-C4H8-N(CH3)2C8H17 (C8-C4-C8))在金电极表面的吸附性能. 结果表明, CC在KNO3溶液中可产生两对峰; 当向溶液中加入阳离子Gemini表面活性剂时, 第一对峰降低, 第二对峰升高, 峰电位差变大; 碳链长的表面活性剂对CC的氧化还原峰的影响较大. 同样, 碳链长的表面活性剂使电极界面的阻抗增大较多, 使石英晶片的频率变化较大. 根据CC的第一个氧化峰的面积随表面活性剂吸附的变化, 估测了它们的吸附模式. 发现这三种表面活性剂在金电极表面的吸附基本符合Langmuir吸附模型.     

Robust synchronization of impulsively-coupled complex switched networks with parametric uncertainties and time-varying delays

This paper presents a general impulsively-coupled complex switched network (ICCSN) model with parametric uncertainties and multiple Time-varying Delays in both the linear and nonlinear terms. The model is more general than those in the literature in that it contains switching behaviors on nodes and impulsive effects in the whole topology. Robust synchronization of ICCSNs with parametric uncertainties and time-varying delays is investigated. Based on the Lyapunov stability theory, delay-independent synchronization conditions for ICCSNs with uncertainties and delays are obtained. In addition, we consider five special synchronization cases: ICCSNs with delays in both the linear and nonlinear terms, ICCSNs with parametric uncertainties and delays either in the linear or in the nonlinear term, ICCSNs without switching behaviors but with parametric uncertainties and delays, and impulsively-switched-coupled complex switched network with uncertainties and delays. A systematic-design procedure is presented, and a numerical example is carried out to demonstrate the effectiveness of the proposed synchronization strategy. A comparative study of the maximum impulsive intervals for synchronization is presented for all special cases.     

Characterization of gold nanoparticles electrochemically deposited on amine-functioned mesoporous silica films and electrocatalytic oxidation of glucose

This study reports the preparation and characterization of gold nanoparticles deposited on amine-functioned hexagonal mesoporous silica (NH₂–HSM) films and the electrocatalytic oxidation of glucose. Gold nanoparticles are fabricated by electrochemically reducing chloroauric acid on the surface of NH₂–HSM film, using potential step technology. The gold nanoparticles deposited have an average diameter of 80 nm and show high electroactivity. Prussian blue film can form easily on them while cycling the potential between −0.2 and 0.6 V (vs saturated calomel electrode) in single ferricyanide solution. The gold nanoparticles loading NH₂–HSM-film-coated glassy carbon electrode (Au–NH₂–HSM/GCE) shows strong catalysis to the oxidation of glucose, and according to the cathodic oxidation peak at about 0.16 V, the catalytic current is about 2.5 μA mM⁻¹. Under optimized conditions, the peak current of the cathodic oxidation peak is linear to the concentration of glucose in the range of 0.2 to 70 mM. The detection limit is estimated to be 0.1 mM. In addition, some electrochemical parameters about glucose oxidation are estimated.     

Si-Fe复合SiOx/石墨基负极材料的电化学性能

针对硅氧基负极材料的主要缺陷,在SiO_x/石墨基负极材料中巧妙地引入了Si-Fe、SnO₂合金化合物,以改善其电化学性能,并通过机械球磨、喷雾干燥和高温热解策略制备了一系列硅氧基复合负极材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱仪(EDS)和恒流充放电测试仪对复合材料的物相、微观形貌及电化学性能进行了表征。电化学测试结果表明,复合质量分数5% Si-Fe的目标材料充电容量高达443.4 mAh·g^-1,首次库仑效率达75.2%,循环310圈之后容量仍有369.1 mAh·g^-1,容量保持率为81.0%(相对第11圈);同时,经Si-Fe复合之后,锂离子扩散速率得到了明显改善。     

Robust synchronization of singular complex switched networks with parametric uncertainties and unknown coupling topologies via impulsive control

This paper presents a general model of singular complex switched networks, in which the nodes can be singular dynamic systems and switching behaviors act on both nodes and edges. The parametric uncertainties and unknown coupling topologies are also considered in this model. Two robust synchronization schemes are discussed respectively. In one scheme, the network is synchronized to a homogeneous orbit and in the other one the network is synchronized to a weighted average of all the nodes. Based on the Lyapunov stability theory, different robust synchronization conditions for the two schemes are obtained for this singular complex switched network model via impulsive control. The similarities and differences between these synchronization conditions for the two schemes are discussed. In addition, three useful robust results for the special cases of the singular complex switched networks are presented. Two systematic-design procedures are presented for the two schemes, and three numerical examples are provided for illustrations.     

Impulsive control for synchronization of a class of continuous systems

An impulsive control theory for synchronization of a class of continuous systems is developed. A sufficient condition for the impulsive control is derived. The proposed impulsive control scheme is illustrated by some continuous chaotic systems and the simulation results demonstrate the effectiveness of the method.     

Adaptive control and synchronization for chaotic systems with parametric uncertainties

An adaptive control scheme using only part of the system states for the stabilization of one chaotic system and the synchronization of two chaotic systems is presented. The system parameters are allowed to have a large range of time varying uncertainties around their fixed unknown nominal values both in the stabilization and the synchronization control problems. Simulation results also illustrate the effectiveness of the proposed control scheme.     

Si-Fe复合SiOx/石墨基负极材料的电化学性能

针对硅氧基负极材料的主要缺陷,在SiO_x/石墨基负极材料中巧妙地引入了Si-Fe、SnO₂合金化合物,以改善其电化学性能,并通过机械球磨、喷雾干燥和高温热解策略制备了一系列硅氧基复合负极材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、能谱仪(EDS)和恒流充放电测试仪对复合材料的物相、微观形貌及电化学性能进行了表征。电化学测试结果表明,复合质量分数5% Si-Fe的目标材料充电容量高达443.4 mAh·g^-1,首次库仑效率达75.2%,循环310圈之后容量仍有369.1 mAh·g^-1,容量保持率为81.0%(相对第11圈);同时,经Si-Fe复合之后,锂离子扩散速率得到了明显改善。