Controllable self-assemblies of β-cyclodextrin-calix[4]arene couples

Amphiphilic cyclodextrin-calixarene conjugates 1 and 2 were synthesized from "click chemistry", and their self-assembly behaviors were investigated by transmission electron microscopy, and atomic force microscopy. The results obtained show that 1 and 2 can self-assemble to form distinctly different aggregations, and the morphology of aggregations critically relies on the polarity and hydrophilicity of the solvent.     

Ce:YVO4晶体的生长及其电荷迁移发光

为探索新型的白光LED荧光粉材料,采用提拉法生长了Ce2(CO3)3掺杂的Ce3+∶YVO4晶体,并对生长晶体的结构和光谱性能进行了表征。通过XRD测试,确定了由提拉法生长的Ce3+∶YVO4晶体的晶相没有发生变化。Ce3+∶YVO4晶体在450 nm处有一个较宽的发射带,在620 nm处有一个明显的发射峰。分析表明,在Ce3+掺杂的YVO4晶体中,铈离子主要以三价离子的形式存在,但在激发光照射下出现的620 nm发射表明有Ce4+存在,并且Ce4+与配位O2-形成了电荷迁移态(CTS)。     

NbB2（0001）表面性质的第一性原理研究

应用密度泛函理论的第一性原理的方法分析了两种不同终端的NbB2(0001)表面的几何结构和电子结构。结果表明:两种不同终端的(0001)表面结构弛豫主要发生在前三层,并且硼终端的表面弛豫程度小于铌终端表面的弛豫。表面能分析结果表明,终止于硼终端的(0001)表面结构在更宽的范围内具有较低的表面能,即硼终端的(0001)表面比铌终端的表面更稳定。进一步分析NbB2(0001)两种终端表面的电子结构表明:在金属铌和硼之间发生了电子转移,加强了化学键的相互作用,导致第一间层向内弛豫。对于铌终端的表面第一层铌转移到第二层的电子数比硼终端表面第二层铌转移到第一层的电子数多,这是导致铌终端表面弛豫程度大于硼终端表面的主要原因。     

共蒸发三步法制备CIGS薄膜的相变过程

本文采用共蒸发三步法沉积Cu(In,Ga)Se2(CIGS)薄膜,其中关于Cu化合物的相转变过程是制约吸收层质量的关键。本文详细研究了三步法工艺中吸收层由贫Cu薄膜向富Cu薄膜转变的相变过程,通过X射线衍射仪(XRD)、X射线荧光光谱仪(XRF)及扫描电镜(SEM)结合的方法总结出三步法工艺的相变过程。     

Statistical scale of hairpin packets in the later stage of bypass transition induced by cylinder wake

The hairpin packet's structure and its statistical scale in the later stage of bypass transition induced by a cylinder wake are investigated by time-resolved particle image velocimetry from the side and top view, respectively. Linear stochastic estimation is used to achieve the conditionally averaged velocity fields. For the side view case, the conditionally averaged structure consists of a series of swirling motions located along a line inclining at a large angle (18°) from the wall and a low-speed region occupied by the cylinder wake appearing right above them. In the (x, z)-plane at the wall-normal height y/???=?0.2, the dominant structures are shown to be the large-scale regions of low momentum elongated almost over 3?? along the streamwise. The low-speed regions are consistently bordered by small-scale counter-rotating vortice pairs organized in the streamwise with a statistical spanwise width of 0.55??. The results suggest that in the later part of the transitional zone, the upward induction of the cylinder wake enhances both the wall-normal and spanwise extent of the hairpin packets.     

A novel bounded 4D chaotic system

This paper presents a novel bounded four-dimensional (4D) chaotic system which can display hyperchaos, chaos, quasiperiodic and periodic behaviors, and may have a unique equilibrium, three equilibria and five equilibria for the different system parameters. Numerical simulation shows that the chaotic attractors of the new system exhibit very strange shapes which are distinctly different from those of the existing chaotic attractors. In addition, we investigate the ultimate bound and positively invariant set for the new system based on the Lyapunov function method, and obtain a hyperelliptic estimate of it for the system with certain parameters.     

Coordinative control of multi-agent systems using distributed nonlinear output regulation

In this paper, the coordinative control problem of a multiagent system with general nonlinear dynamics is addressed. This multiagent coordination problem can be formulated as a nonlinear output regulation problem, and in order to solve it, the nonlinear distributed coordinative control is designed to make the agents asymptotically track the reference or reject disturbance. The reference or disturbance signals are generated by an exosystem, which can be considered as active leaders or the environmental disturbance in the considered multiagent systems. Finally, an illustrative example is provided to demonstrate the effectiveness of the main results.     

A hyperchaotic system without equilibrium

This article introduces a new chaotic system of 4-D autonomous ordinary differential equations, which has no equilibrium. This system shows a hyper-chaotic attractor. There is no sink in this system as there is no equilibrium. The proposed system is investigated through numerical simulations and analyses including time phase portraits, Lyapunov exponents, and Poincaré maps. There is little difference between this chaotic system and other chaotic systems with one or several equilibria shown by phase portraits, Lyapunov exponents and time series methods, but the Poincaré maps show this system is a chaotic system with more complicated dynamics. Moreover, the circuit realization is also presented.     

Research on the price game model for four oligarchs with different decision rules and its chaos control

Based on the actual competition in the Chinese property insurance market, the repeated price game model for four oligarchs with different decision rules is built. On the basis of analyzing the stabilities of eight fixed points about the four-dimensional dynamic system, the Nash equilibrium and its local stable region are discussed mainly. Then the complexity of the four-dimensional discrete dynamic system and its evolutionary process are studied. Finally, the delay feedback control method is used to control the chaos. Numerical simulation results have shown that the influence which the change of price adjustment speed has on the movement of dynamic system has a sensitive dependence on the initial conditions, and there is a strong connection between the profit of each oligarch and the price adjustment speed or the control parameters, and the corresponding economic explanation to those phenomena will have important reference values to the realistic problems.