Sampled-data nonlinear observer design for chaos synchronization: A Lyapunov-based approach

This paper considers sampled-data based chaos synchronization using observers in the presence of measurement noise for a large class of chaotic systems. We study discretized model of chaotic systems which are perturbed by white noise and employ Lyapunov-like theorems to come up with a simple yet effective observer design. For the choice of observer gain, a suboptimal criterion is obtained in terms of LMI. We present semiglobal as well as global results. The proposed scheme can also be extended for discrete-time chaotic systems. Numerical simulations have been carried out to verify the effectiveness of theoretical results.     

Nonlinear separation approach for the augmented Lagrangian in nonlinear semidefinite programming

This paper aims at showing that the class of augmented Lagrangian functions for nonlinear semidefinite programming problems can be derived, as a particular case, from a nonlinear separation scheme in the image space associated with the given problem. By means of the image space analysis, a global saddle point condition for the augmented Lagrangian function is investigated. It is shown that the existence of a saddle point is equivalent to a regular nonlinear separation of two suitable subsets of the image space. Without requiring the strict complementarity, it is proved that, under second order sufficiency conditions, the augmented Lagrangian function admits a local saddle point. The existence of global saddle points is then obtained under additional assumptions that do not require the compactness of the feasible set. Motivated by the result on global saddle points, we propose two modified primal-dual methods based on the augmented Lagrangian using different strategies and prove their convergence to a global solution and the optimal value of the original problem without requiring the boundedness condition of the multiplier sequence.     

基于保守决策偏好的犹豫模糊余弦优化投影决策方法

针对犹豫模糊信息下的多属性决策问题,提出了余弦优化投影方法,将投影夹角定义为决策者的风险偏好,并设置了态度参数用于调节决策者的心理变化,通过灵活描述决策者的保守心理,改进了投影法仅考虑投影长度的不足,使决策者可通过投影长度和投影夹角对备选方案进行综合判断。算例验证了方法的合理性和可行性。     

一种线性模型的精确转换方法

基于广义范德蒙矩阵的逆矩阵的计算方法,导出线性系统的连续时间模型和离散时间模型在含有重极点时的严格的直接换算关系,其结果可以直接表示为两者的分子多项式系数之间的关系,并且,对不同的调制器具有统一的转换形式.     

Steady viscoelastic film flow over 2D topography: I. The effect of viscoelastic properties under creeping flow

Two-dimensional, steady flow of a viscoelastic film over a periodic topography under the action of a body force is studied. The exponential Phan-Thien and Tanner (ePTT) constitutive model is used. The conservation equations are solved via the usual mixed finite element method combined with a quasi-elliptic grid generation scheme in order to capture the large deformations of the free surface. The constitutive equation is weighted using the SUPG method and solved via the polymeric stress splitting EVSS-G technique. First, the code is validated by verifying that in isolated topographies the periodicity conditions result in fully developed viscoelastic film flow at the inflow/outflow boundaries and that its predictions for Newtonian fluids over 2D topography under creeping flow conditions coincide with those of previous works. Since the lubrication approximation is not invoked here, the topographical features can have wall segments that form any angle with the main flow, but only slight smoothing of the convex corners assists in reducing the stress singularity there. Thus, steady-state solutions are computed accurately up to high Deborah numbers, resulting in large deformations of the free surface. The magnitude of the capillary ridge in the film before the entrance to a step down of the substrate and of the capillary depression before a step up is increased as De increases up to ～0.7 due to increased fluid elasticity. Above this value they decrease, because increasing De increases also the shear and elongational thinning, which eventually affect them more. Increasing the ratio of solvent to polymer viscosities, β, the elongational parameter, ? and the molecular slip parameter, ξ, monotonically increases their magnitudes and especially that of the capillary ridge, but the mechanisms leading to these changes are different as explained in the text.     

Solubility and stability of recurrent neural networks with nonlinearity or time-varying delays

Because to apply a deterministic RNN to a noisy time series and the existence of a linear approximation are doubtful, we reconsider the solubility and stability of a recurrent neural network (RNN). Simpler methods are proposed to replace the complicated nonsingular M-matrix method when nonlinearities exist and to replace the complicated linear matrix inequality method when time-varying delays exist.     

Design and application of feedback-sustained target waves in excitable medium

In this paper, we present a formulas of rational ratios between the frequency of external stimulus and its paced target waves, considering the existence of the absolute refractory period and the relative refractory period. Based on this, we design a self-sustained high-frequency target waves by feeding back few periphery field points to the center to responsibly play the role of source for pacemaker. Such constructed target waves, to all appearances, are shown as a repetition of their initial condition. We explore further in application that those feedback-sustained targets can eliminate both a freely rotating spiral waves and a pinned ones only if frequencies, feedback lengths and radius of obstacles are appropriately chosen. After feedback stimuli are removed, the system eventually returns to the rest state.     

Preparation and characterization of the antimony telluride hexagonal nanoplates

Nanostructured thermoelectric materials are of much interest for improving the thermoelectric figure of merit. In the present work, Sb₂Te₃ hexagonal nanoplates were successfully fabricated via a facile hydrothermal method. The products were characterized by means of X-ray diffraction, field-emission scanning electron microscope, transmission electron microscope and energy-dispersive X-ray spectroscopy. The results show that the typical Sb₂Te₃ crystal is hexagonal in shape with about 35 nm in thickness and 300 nm in edge length. The mechanism for formation of Sb₂Te₃ hexagonal nanoplates is primarily discussed.     

Multi-radius centralized projection for binary pattern histogram face recognition

The existing local binary pattern （LBP） operators have several disadvantages such as rather long histograms, lower discrimination, and sensitivity to noise. Aiming at these problems, we propose the central- ized binary pattern （CBP） operator. CBP operator can significantly reduce the histograms＇ dimensionality, offer stronger discrimination, and decrease the white noise＇s influence on face images. Moreover, for in- creasing the recognition accuracy and speed, we use multi-radius CBP histogram as face representation and project it onto locality preserving projection （LPP） space to obtain lower dimensional features. Experiments on FERET and CAS-PEAL databases demonstrate that the proposed method is superior to other modern approaches not only in recognition accuracy but also in recognition speed.