A new method for control chaos based on delay feedback of system variables is proposed. The control results of three typical chaotic systems are given. The method of control chaos can be easily realized in physical systems, for the control price of this method is low. The mechanism of the method is also discussed based on varied of average value of Lyapunov function.

In this paper, a kind of chaos encryption system is presented based on chaotic encryption algorithm and traditional encryption algorithm, and hardware is implemented by using the FPGA technology. According to discrete and digital technologies, Henon Map and Logistic Map are applied, and chaotic iteration sequence is generated by using Verilog HDL language and FPGA technology. By combining the traditional iteration algorithm, the files are encrypted and decrypted. Based on Xilinx FPGA exploitation platform, secret communication experiments on Internet are successefully. The devise has potential prospective applications in internet secrecy communication.

In this paper,the bifurcation behaviour and chaos control are investigated for a DC-DC buck converter with load capacitor.Some valuable new results are obtained,e.g.,the periodicity adding windows are found in this circuit system and the measure of chaotic motion is found to converge to zero asymptotically increasing load capacitance.Moreover,it is found that the transform ratio of voltage for periodict motion is higher than that for the chaotic motion in the buck converter.These results have some applications for designing practical circuits.At the same time,chaotic behaviours of this circuit system can be effectively controlled by applying suitable periodic impulses to the system.

The ionic beam which exhibits a Kapchinsky_Vladimirsky distribution is studied in this paper. Not only the halo is found, but also the ionic radial den sity which has changed is discovered when the ionic beam is in accelerator chan nels. By delay feedback control method, the halo is removed. Moreover as long as the proper parameters are chosen, the density uniformity can be found at beam' s center.

Exploiting the information provided by the number of ions in some fixed regions outside the matched radius boundary, the simulation of controlling the beam halo-chaos of a high intensity ion beam has been studied by applying the logarithm-function controller. Control results show that the halo-chaos and its regeneration can be eliminated effectively for five different initial distributions, respectively. The controlling method is easy to realize in experiment because it only needs to probe the control information in small and fixed regions.