Adaptive control of bifurcation and chaos in a time-delayed system

In this paper, the stabilization of a continuous time-delayed system is considered. To control the bifurcation and chaos in a time-delayed system, a parameter perturbation control and a hybrid control are proposed. Then, to ensure the asymptotic stability of the system in the presence of unexpected system parameter changes, the adaptive control idea is introduced, i.e., the perturbation control parameter and the hybrid control parameter are automatically tuned according to the adaptation laws, respectively. The adaptation algorithms are constructed based on the Lyapunov-Krasovskii stability theorem. The adaptive parameter perturbation control and the adaptive hybrid control methods improve the corresponding constant control methods. They have the advantages of increased stability, adaptability to the changes of the system parameters, control cost saving, and simplicity. Numerical simulations for a well-known chaotic time-delayed system are performed to demonstrate the feasibility and superiority of the proposed control methods. Besides, comparison of the two adaptive control methods are made in an experimental study.     

Parametric study of control mechanism of cortical bone remodeling under mechanical stimulus

The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.     

Dependences of spin polarization on the control parameters in the spin-polarized injection through the magnetic p-n junction

Effective spin-polarized injection from magnetic semiconductor (MS) to nonmagnetic semiconductor (NMS) has been highlighted in recent years. In this paper we study theoretically the dependence of nonequilibrium spin polarization (NESP) in NMS during spin-polarized injection through the magnetic p-n junction. Based on the theory in semiconductor physics, a model is established and the boundary conditions are determined in the case of no external spin-polarized injection and low bias. The control parameters that may influence the NESP in NMS are indicated by calculating the distribution of spin polarization. They are the doping concentrations, the equilibrium spin polarization in MS and the bias. The effective spin-polarized injection can be realized more easily by optimizing the above parameters.     

Hopf Bifurcation Control of a Hyperchaotic Circuit System

This paper is concerned with the Hopf bifurcation control of a new hyperchaotic circuit system. The stability of the hyperchaotie circuit system depends on a selected control parameter is studied, and the critical value of the system parameter at which Hopf bifurcation occurs is investigated. Theoretical analysis give the stability of the Hopf bifurcation. In particular, washout filter aided feedback controllers are designed for delaying the bifurcation point and ensuring the stability of the bifurcated limit cycles. An important feature of the control laws is that they do not result in any change in the set of equilibria. Computer simulation results are presented to confirm the analytical predictions.     

电梯驱动的参数自动优化

本文介绍了罗尔Dynavert 1.05电梯专用变频器对电梯驱动的控制参数进行自动优化的做法，这对缩短电梯变频调速系统的调试周期以及提高电梯的运行性能是至关重要的。     

基于LOCO-Ⅰ算法的图像压缩比控制

在认真研究LOCO-Ⅰ算法的基础上,深入分析了失真控制参数Near对图像压缩比和重建质量的影响,通过对该算法中的Near进行实时动态调整,实现了对图像近无损压缩的压缩比控制,进而可以根据需求来控制图片大小进行压缩.仿真结果表明,提出的压缩比控制方案收敛性较好,输出码流稳定,在满足目标压缩比时重建图像质量较原一阶压缩比控制方案提高了0.5 dB左右.     

激光焊机走行小车变频器的故障分析

本文对激光焊机伺服小车变频器“直流过电压”故障进行处理，从系统的角度对该故障现象进行了理论分析，对分析与处理同类故障具有一定指导意义。     

Mechanical effects of light on the Ξ-type three-level atom in a high-finesse optical cavity

A theoretical study is carried out for the modification and implication of the effect on the Ξ-type three level atom in a high-finesse optical cavity driven by light field including spontaneous emission and the cavity decay. Analytic expressions for the dipole force, the friction force, the optical potentials and the friction coefficient are obtained. Then the numerical and graphical methods are used to investigate the friction coefficient with the controlling parameters. It is shown that the friction coefficient is strongly dependent on the controlling parameters. The cooling rate can increase by one order of magnitude more than that of a two-level atomic system. The reason can be given using the dressed states and the Sisyphus cooling mechanism, which would stimulate further experimental investigations.     

GSM网络覆盖铁路的工程设计

移动通信市场竞争的日趋激烈以及移动通信技术的飞速发展都对我们网络维护人员提出了更高的要求:应该综合利用各种通信技术,不断优化网络,提高网络的投资效益,以获得领先的网络竞争优势。移动通信相对于固定网络的优势在于其特有的“移动性”,在任何移动条件下提供畅通的网络服     

基于外参考速度辅助的行进间罗经法对准

为实现行进间罗经法对准,将外参考速度引入,同时设计不同机动方式下的罗经法控制回路参数调节规律提高对准精度、缩短对准时间。首先分析线运动对罗经法对准造成的影响,设计基于外速度辅助的行进间罗经法对准方案;然后利用对准回路传递函数进行误差分析,分析不同机动给对准精度造成的影响;最后提出不同机动方式下的罗经法对准回路控制参数设置规律。仿真结果表明基于外速度辅助的行进间罗经法对准能有效完成捷联惯导在匀速直线运动中的对准。根据设置规律调节对准回路中的控制参数,可以抑制80%以上由载体摇摆造成的低频干扰,将航向误差的振荡幅值降低为原来的1/2,有效提高了对准精度。