Biomedical subjects

Xiaofeng Liao

Publications and source records attributed to Xiaofeng Liao.

14 recordsLinked to original sources

PubMed2006

Chaos quasisynchronization induced by impulses with parameter mismatches.

This paper studies the effect of parameter mismatch on the impulsive synchronization of a class of coupled chaotic systems. A new definition for global quasisynchronization is introduced and used to analyze the synchronous behavior of coupled chaotic systems in the presence of parameter mismatch. Using the linear decomposition and comparison-system methods, a global synchronization error bound together with a sufficient condition is derived. Numerical simulations on the chaotic Chua's circuit are presented to verify the theoretical results.

Algorithms↗

PubMed2006

Switch control for piecewise affine chaotic systems.

Switch control can be imposed naturally on the piecewise affine system, where the control action switches from an affine subsystem to another according to switch conditions depending on the system states. In this paper we present such piecewise feedback control for stabilizing unstable equilibrium points of piecewise affine systems. The noise effect on the stabilization is also investigated. The original Chua's circuit is used to illustrate our results.

Algorithms↗

PubMed2006

Stability analysis and H infinity controller design of fuzzy large-scale systems based on piecewise Lyapunov functions.

This paper presents a novel approach to stability analysis of a fuzzy large-scale system in which the system is composed of a number of Takagi-Sugeno (T-S) fuzzy subsystems with interconnections. The stability analysis is based on Lyapunov functions that are continuous and piecewise quadratic. It is shown that the stability of the fuzzy large-scale systems can be established if a piecewise Lyapunov function can be constructed, and, moreover, the function can be obtained by solving a set of linear matrix inequalities (LMIs) that are numerically feasible. It is also demonstrated via a numerical example that the stability result based on the piecewise quadratic Lyapunov functions is less conservative than that based on the common quadratic Lyapunov functions. The H infinity controllers can also be designed by solving a set of LMIs based on these powerful piecewise quadratic Lyapunov functions.

Algorithms↗

PubMed2005

Impulsive synchronization of chaotic systems.

The issue of impulsive synchronization of a class of chaotic systems is investigated. Based on the impulsive theory and linear matrix inequality technique, some less conservative and easily verified criteria for impulsive synchronization of chaotic systems are derived. The proposed method is applied to the original Chua oscillators, and the corresponding synchronization conditions are obtained. Moreover, the boundary of the stable region is also estimated in terms of the equidistant impulse interval. The effectiveness of our method is shown by computer simulation.

Algorithms↗

PubMed2005

Impulsive stabilization and synchronization of a class of chaotic delay systems.

The problems of control and synchronization of a class of chaotic systems with time delay via the impulsive control approach are investigated. Based on the Lyapunov-like stability theory for impulsive functional differential equations, several sufficient conditions are derived to guarantee chaos control and synchronization. Furthermore, we address the chaos quasisynchronization in the presence of single-parameter mismatch. Several illustrated examples are also given to show the effectiveness of the proposed methods.

Journal Article↗

PubMed2004

Bifurcation analysis on a two-neuron system with distributed delays in the frequency domain.

In this paper, a general two-neuron model with distributed delays and a strong kernel is investigated. By applying the frequency domain approach and analyzing the associated characteristic equation, the existence of bifurcation parameter for the model is determined. Furthermore, if the mean delay used as a bifurcation parameter, it is found that Hopf bifurcation occurs for the strong kernel. This means that a family of periodic solutions bifurcates from the equilibrium when the bifurcation parameter exceeds a critical value. The direction and stability of the bifurcating periodic solutions are determined by the Nyquist criterion and the graphical Hopf bifurcation theorem. Some numerical simulations are given to justify the theoretical analysis results.

Computer Simulation↗

PubMed2004

Criteria for exponential [corrected] stability of Cohen-Grossberg neural networks.

In this paper, the Cohen-Grossberg neural network models without and with time delays are considered. By constructing several novel Lyapunov functionals, some sufficient criteria for the existence of a unique equilibrium and global exponential stability of the network are derived. These results are fairly general and can be easily verified. Besides, the approach of the analysis allows one to consider different types of activation functions, including piecewise linear, sigmoids with bounded activations as well as C1-smooth sigmoids. In the meantime, our approach does not require any symmetric assumption of the connection matrix. It is believed that these results are significant and useful for the design and applications of the Cohen-Grossberg model.

Neural Networks, Computer↗

PubMed2004

Robust stability of interval bidirectional associative memory neural network with time delays.

In this paper, the conventional bidirectional associative memory (BAM) neural network with signal transmission delay is intervalized in order to study the bounded effect of deviations in network parameters and external perturbations. The resultant model is referred to as a novel interval dynamic BAM (IDBAM) model. By combining a number of different Lyapunov functionals with the Razumikhin technique, some sufficient conditions for the existence of unique equilibrium and robust stability are derived. These results are fairly general and can be verified easily. To go further, we extend our investigation to the time-varying delay case. Some robust stability criteria for BAM with perturbations of time-varying delays are derived. Besides, our approach for the analysis allows us to consider several different types of activation functions, including piecewise linear sigmoids with bounded activations as well as the usual C1-smooth sigmoids. We believe that the results obtained have leading significance in the design and application of BAM neural networks.

Journal Article↗

PubMed2003

Synchronization of fractional order chaotic systems.

The chaotic dynamics of fractional order systems began to attract much attention in recent years. In this Brief Report, we study the master-slave synchronization of fractional order chaotic systems. It is shown that fractional order chaotic systems can also be synchronized.

Journal Article↗

PubMed2003

Global exponential stability of hybrid bidirectional associative memory neural networks with discrete delays.

In this paper, the dynamical characteristics of hybrid bidirectional associative memory neural networks with constant transmission delays are investigated. Without assuming symmetry of synaptic connection weights and monotonicity and differentiability of activation functions, Halanay-type inequalities (which are different from the approach of constructing Lyapunov functionals) are employed to derive the delay-independent sufficient conditions under which the networks converge exponentially to the equilibria associated with temporally uniform external inputs. Our results are less conservative and restrictive than previously known results.

Algorithms↗

PubMed2003

Expression of angiogenic factors in hepatocellular carcinoma after transcatheter arterial chemoembolization.

In order to investigate the changes of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) expression in residual hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE), the expression levels of VEGF and bFGF expression in specimens surgically removed from 48 HCC patients were detected by immunohistochemical methods, and staining intensity of VEGF and bFGF was assessed by a computer-assisted image-analyzer. Among the 48 patients, 25 underwent partial hepatectomy alone (single operating group), and 23 were subjected to second stage surgical resection after TACE (TACE group). The results showed that the average absorbance value (A) of VEGF was higher in TACE group than that in single operating group (0.152 +/- 0.021 vs 0.131 +/- 0.012, P < 0.01). The Average A of bF-GF in TACE group was 0.127 +/- 0.023, higher than in single operating group (0.111 +/- 0.016, P < 0.05). These results suggested that TACE of HCC can up-regulate the expression of VEGF and bFGF in HCC tissues possibly due to anoxia and ischemia.

Aged↗

PubMed2003

Global and robust stability of interval Hopfield neural networks with time-varying delays.

In this paper, we investigate the problem of global and robust stability of a class of interval Hopfield neural networks that have time-varying delays. Some criteria for the global and robust stability of such networks are derived, by means of constructing suitable Lyapunov functionals for the networks. As a by-product, for the conventional Hopfield neural networks with time-varying delays, we also obtain some new criteria for their global and asymptotic stability.

Algorithms↗

PubMed2003

Novel stability criteria for delayed cellular neural networks.

In this paper, a new sufficient condition is given for the global asymptotic stability and global exponential output stability of a unique equilibrium points of delayed cellular neural networks (DCNNs) by using Lyapunov method. This condition imposes constraints on the feedback matrices and delayed feedback matrices of DCNNs and is independent of the delay. The obtained results extend and improve upon those in the earlier literature, and this condition is also less restrictive than those given in the earlier references. Two examples compared with the previous results in the literatures are presented and a simulation result is also given.

Algorithms↗

PubMed2002

Delay-dependent exponential stability analysis of delayed neural networks: an LMI approach.

For neural networks with constant or time-varying delays, the problems of determining the exponential stability and estimating the exponential convergence rate are studied in this paper. An approach combining the Lyapunov-Krasovskii functionals with the linear matrix inequality is taken to investigate the problems, which provide bounds on the interconnection matrix and the activation functions, so as to guarantee the systems' exponential stability. Some criteria for the exponentially stability, which give information on the delay-dependence property, are derived. The results obtained in this paper provide one more set of easily verified guidelines for determining the exponentially stability of delayed neural networks, which are less conservative and less restrictive than the ones reported so far in the literature.

Algorithms↗