Results 1 - 10 of 14
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[en] Robust control problem of nonlinear time-delay chaotic systems is investigated. For such uncertain systems, we propose adaptive feedback controller and novel nonlinear feedback controller. They are both independent of the time delay and can render the corresponding closed-loop systems globally uniformly ultimately bounded stable. The simulations on controlling logistic system are made and the results show the controllers are feasible
[en] Control problem of chaotic system is investigated via adaptive method. A fairly simple adaptive controller is constructed, which can control chaotic systems to unstable fixed points. The precise mathematical models of chaotic systems need not be known and only the fixed points and the dimensions of chaotic systems are required to be known. Simulations on controlling different chaotic systems are investigated and the results show the validity and feasibility of the proposed controller
[en] In this note, the problem of control for a class of chaotic systems is studied. Only partial information of the systems states is known. First, an adaptive observer is designed to ensure the corresponding error system asymptotically stable. Then, based on the states obtained by the above observer, a nonlinear state feedback controller is constructed for the chaotic system, which, according to the input to state stable (ISS) principal, guarantees the closed-loop chaotic system is asymptotically stable. A numerical example is included to show the effectiveness of the proposed techniques
[en] In this paper, the problem of control for a class of chaotic systems is considered. The nonlinear functions of chaotic systems are not necessarily to satisfy the Lipsichtz conditions, but bounded by a polynomial with the gains unknown. Employing adaptive method, the corresponding controller which renders the closed-loop system asymptotically stable is constructed. The designed controller is robust with respect to certain class of disturbances in the chaotic systems. Simulations on unified chaotic systems and Arneodo chaotic system are performed and the results verify the validity of the proposed techniques
[en] The laser-atomic-beam spectroscopy technique has been used to make measurements of the hyperfine structure in some odd parity levels of thulium by stepwise excitation. With the experimental results the magnetic dipole hyperfine constants A for the four levels in the configurations 4f12 5d6s6p and 4f12(3H5)6s26p3/2 and for two intermediate levels have been obtained. (orig.)
[en] The aluminium-doped zinc oxide with buffer layer films were deposited on the polyethylene terephthalate substrates by radiofrequency magnetron sputtering. Compared with the AZO films without buffer layer, the crystallite size and (002) peak of the films changed with the deposition times; the full-width at half-maximum (FWHM) of (002) peak decreases from 0 to 25 min. The effects of buffer layer on the surface morphology of and optical properties of films were investigated by SEM and UV–Vis–NIR spectrophotometer, respectively. The results reveal that the average transmittance of the AZO films in the visible wavelength region is , stronger deep level emissions centred on 550 nm is attributed to intrinsic defects in the AZO films on the organic polymer PET substrates.
[en] Synchronization problem of chaotic systems via observer method is investigated. In contrast to the results of the literatures, we consider the case that there exist noise disturbances in the output. Under this condition, it is not ideal to employ the classic observer to solve the synchronization problem. The proportional integral observer is proposed, which can render the error system stable with the noise in the output. Simulations on synchronizing Chua chaotic systems are done to verify the effectiveness of the main results
[en] In this Letter the time delay dependent stability problem is investigated for a class of time delay neural networks. By constructing novel Lyapunov Krasovskii functional, we propose the new stability results for time delay neural network. The sufficient conditions obtained in this Letter are looser than those in the former literature. Specially, our results include the time delay independent results obtained in some existing literature. The stability conditions are all in the form of linear matrix inequalities (LMIs), which can be computed and optimized easily. Finally, numerical examples are given to show the superiority of the main results
[en] In this paper, we address the issue of synchronization for two identical chaotic systems with time-varying delays and uncertainties under sampled-data control. By developing some new terms, an improved piecewise Lyapunov–Krasovskii functional (LKF) is constructed to take full advantage of characteristic about real sampling and nonlinear function vector. Furthermore, some relaxed matrices constructed in LKF are not necessarily positive definite. By using the LKF and free-matrix-based integral inequality, some sufficient criteria can be obtained to ensure the stability of error systems and reduce the influence of external disturbances with an norm bound. The sampled-data controller can be synthesized by solving a group of linear matrix inequalities with the maximal sampling interval. Finally, the numerical examples are considered and analyzed by the proposed approach so as to show the benefit and the superiority of the proposed approach.
[en] Eleven new lifetimes of odd parity excited energy levels in four configurations: 4f12 5d 6s 6p, 4f12 6s2 6p, 4f13 5d 6s and 4f13 6s 7s of atomic thulium have been measured with atomic-beam laser spectroscopy. Two pulsed dye lasers are used for stepwise excitation and the time-resolved fluorescent decay was used to determine lifetime values. The accuracy of the measurements is about 10%. (orig.)