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The paper addresses the fixed-/preassigned-time synchronization of stochastic memristive neural networks (MNNs) with uncertain parameters and mixed delays. Adaptive sliding mode control (ASMC) technology is mainly utilized. First, a proper sliding surface is constructed and the adaptive laws are given. Also, the synchronization control scheme is designed, which can ensure error system to realize fixed-time stability. Second, preassigned-time sliding mode control scheme is mainly provided to realize fast synchronization of MNNs. The presented theoretical methods can guarantee the error system convergence and stability for reaching and sliding mode within preassigned-time. And the synchronization criteria and explicit expression of settling time (ST) are acquired, where ST is not related with initial values and controller parameters but can be predefined perferentially. Finally, the calculation example is offered to interpret the practicability and availability of the innovations in this paper. [ABSTRACT FROM AUTHOR]

Falls are the main cause of increased morbidity and mortality in the elderly. Human activity recognition is a difficult task due to factors such as light changes and complex background. To address these challenges, this paper proposes a method for recognizing falling activity based on the human skeleton and optical flow sequence. First, videos of fall activities and not-fall activities of different testers are captured using the Kinect v2 sensor; then, the captured videos are pre-processed to obtain the skeleton images and grayscale images of each activity; and the optical flow sequences of adjacent images are obtained using the dense optical flow algorithm. This paper proposes a lightweight convolutional neural network for extracting movement features from multimodal data and identifying activities. The decision fusion algorithm combines the fuzzy comprehensive evaluation method and the majority voting strategy to determine the weight values that influence the final decision outcomes. The experimental results show that the accuracy of the method proposed in this paper is up to 95.31%, which has a good effect on the recognition of falling activity. [ABSTRACT FROM AUTHOR]

This paper presents a new design approach to achieve decentralized optimal control of nonlinear singularly perturbed interconnected systems based on Takagi-Sugeno fuzzy model. Due to the existence of slow and fast phenomena in the fuzzy singularly perturbed interconnected systems, which brings computational errors when solving the coupled algebraic Riccati equation. Therefore, a model-based parallel hybrid iterative method is proposed, in which system dynamics are required. On this basis, a model-free parallel hybrid reinforcement learning method is proposed. As a consequence, compared with policy iteration, the proposed parallel hybrid reinforcement learning method is independent of an initial admissible controller. Finally, the effectiveness of the proposed method is verified through a numerical example. [ABSTRACT FROM AUTHOR]

Gait recognition is significant in the fields of disease diagnosis and rehabilitation training by studying the characteristics of human gait with different terrain. To address the problem that the transformation of different outdoor terrains can affect the gait of walkers, a gait recognition algorithm based on feature fusion with attention mechanism is proposed. First, the acceleration, angular velocity and angle information collected by the inertial measurement unit is used; then the acquired inertial gait data is divided into periods to obtain the period data of each step; then the features are extracted from the data, followed by the visualization of the one-dimensional data into two-dimensional images. A lightweight model is designed to combine convolutional neural network with attention mechanism, and a new attention mechanism-based feature fusion method is proposed in this paper for extracting features from multiple sensors and fusing them for gait recognition. The comparison experimental results show that the recognition accuracy of the model proposed in this paper can reach 89 % , and it has good recognition effect on gait under different terrain. [ABSTRACT FROM AUTHOR]

This paper concentrates on the issues of input–output finite-time stability (IO-FTS) and finite-time boundedness (FTB) for stochastic Takagi–Sugeno fuzzy nonlinear systems. The novel sufficient criterion regarding IO-FTS and FTB is derived. A state observer is built, which can estimate state that are difficult to measure. Using the constructed state observer and an observer-based event-triggered protocol, the event-triggered controller is constructed. The observer gains and controller gains can be derived from the obtained sufficient conditions. Furthermore, the practicality and feasibility for the presented control scheme are proven using a numerical example and an example of an inverted pendulum on a trolley system. [ABSTRACT FROM AUTHOR]

This paper considers the finite-time synchronization problem of stochastic complex networks with mixed delays. A controller based on adaptive aperiodic intermittent control strategy is constructed, which can guarantee that network systems with unknown characteristics of the controlled object or a wide range of disturbance characteristics achieve synchronization in the finite-time. Moreover, relying on various inequality techniques, the finite-time synchronization criterion is obtained by establishing the Lyapunov function. Then, the synchronization of the stochastic network system can still be achieved, when the stochastic disturbance does not exist. Finally, the rationality of the theoretical results is tested by an example of Chua's circuit system. [ABSTRACT FROM AUTHOR]

The finite-time bounded problem for stochastic nonlinear singular systems is discussed in this paper. Firstly, the state observer independent of external disturbances and Brownian motions is designed. Next, the sliding mode function is constructed, which can not only ensure that the system is the finite-time bounded stability, but also its H ∞ performance can be satisfied. The criteria for the finite-time bounded stability and H ∞ finite-time bounded stability of the given system are obtained by Lyapunov function and linear matrix inequalities. Combined with the designed controller, the finite-time stability of the sliding mode function is guaranteed. Finally, the practicability of the control scheme designed is verified by two examples. [ABSTRACT FROM AUTHOR]

This paper focuses on the ℋ ∞ synchronization issue for fuzzy neural networks via a dynamic event-triggered sliding mode control scheme. In order to relieve the congestion phenomenon in the communication channel, a dynamic event-triggered mechanism is introduced into the sliding mode control design, in which an internal dynamical variable is adopted to fit the event-triggered condition suitably. Moreover, some results with less conservatism are obtained by considering the asynchronous premise variable problem. Then, sufficient criteria are established through the Lyapunov stability theory, which can guarantee that the sliding mode dynamics is asymptotically stable with a given ℋ ∞ performance. In this case, a dynamic event-triggered sliding mode control law is constructed to drive the trajectories of the fuzzy neural networks onto the designed sliding surface. Finally, the effectiveness and superiority of the presented method is verified by an illustrative example. [ABSTRACT FROM AUTHOR]

This paper aims to address the fault-tolerant control problem for a class of discrete-time Takagi–Sugeno fuzzy Markov jump systems, where Markov process is introduced to represent the structural changes in system parameters. And a group of Bernoulli distributed white variables are introduced to characterize the random gain variations. Also, according to Lyapunov stability theory, a set of sufficient conditions which can achieve the mean square stochastic stability with an extended dissipative performance index of the closed-loop systems are established. In the end, the effectiveness of the method proposed in this paper is illustrated by analyzing a numerical example. [ABSTRACT FROM AUTHOR]

This paper investigates the stability of power systems with load frequency control considering time delays (constant and time-varying delays). A new criterion for ensuring the stability of the system is proposed on the basis of Lyapunov stability theory and a further strengthened inequality. Finally, taking a single-area load frequency control scheme with the proportional-integral controller as an example, according to the stability criterion obtained, the relationship between the maximum allowable delay and the gain of proportional-integral controller is discussed. Besides, in case studies, the effectiveness of our method is also demonstrated. [ABSTRACT FROM AUTHOR]

The current work has proposed an approach to the controller design of a fuzzy non-singular terminal sliding mode (NTSM) for a type of planar systems with input saturation. On the basis of a modified version of NTSM, a category of saturated NTSM controller is first constructed to ensure that the states can reach the sliding surface and finite-time converge to the origin. On this basis, a fuzzy logic controller including two fuzzy input variables and a fuzzy output variable is developed to adaptively adjust the control gain such that the gain of the NTSM controller can be automatically minimized. This also implies that the chattering phenomenon encountered by most conventional sliding mode control (SMC) schemes can be significantly attenuated without sacrificing inherent properties. Finally, in comparison with a traditional SMC method, the superiority of the presented algorithm is confirmed by the comparative simulation results in terms of chattering alleviation and robustness. [ABSTRACT FROM AUTHOR]

This paper deals with the problem for synchronization of a nonlinear time delayed complex spatio-temporal network (CSN), modelled by semi-linear parabolic partial differential-difference equations. A boundary controller relying to distributed measurement is designed. Multiple time-invariant delays are firstly considered. By employing Lyapunov's direct method and Wirtingers inequality, synchronization criteria of the CSN are presented in terms of LMIs. And then, multiple time-varying delays are respectively considered using the boundary controller and synchronization criteria are obtained. Finally, an example illustrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The target of this article is to study almost periodic dynamical behaviors for complex-valued recurrent neural networks with discontinuous activation functions and time-varying delays. We construct an equivalent discontinuous right-hand equation by decomposing real and imaginary parts of complex-valued neural networks. Based on differential inclusions theory, diagonal dominant principle and nonsmooth analysis theory of generalized Lyapunov function method, we achieve the existence, uniqueness and global stability of almost periodic solution for the equivalent delayed differential network. In particular, we derive a series of results on the equivalent neural networks with discontinuous activation functions, constant coefficients as well as periodic coefficients, respectively. Finally, we give a numerical example to demonstrate the effectiveness and feasibility of the derived theoretical results. [ABSTRACT FROM AUTHOR]

In this paper, the almost periodic dynamical behaviors are considered for delayed complex-valued neural networks with discontinuous activation functions. We decomposed complex-valued to real and imaginary parts, and set an equivalent discontinuous right-hand equation. Depended on the differential inclusions theory, diagonal dominant principle, non-smooth analysis theory and generalized Lyapunov function, sufficient criteria are obtained for the existence uniqueness and global stability of almost periodic solution of the equivalent delayed differential system. Especially, we derive a series of results on the equivalent neural networks with discontinuous activations and periodic coefficients or constant coefficients, respectively. Finally, we give one numerical example to demonstrate the effectiveness of the derived theoretical results. [ABSTRACT FROM AUTHOR]

The study, by using aperiodically intermittent pinning control, is to synchronize switched delayed complex networks with unstable subsystems. Matrix ω-measure and mode-dependent average dwell time method are used to achieve globally exponential synchronization for such system. By designing the useful switching rule and control scheme, we obtain the novel synchronization criteria, which improve the conventional results. Finally, simulation analysis demonstrates the advantages of proposed innovations. [ABSTRACT FROM AUTHOR]

This paper mainly investigates finite-time synchronization of multiple different-order chaotic systems. Two kinds of different network synchronization modes are considered here, and the definitions of finite-time synchronization errors are given for such systems by constructing the proper vectors mapping functions. On the basis of finite-time control idea, the synchronization schemes are developed to ensure the asymptotical stability of two classes of different error systems in finite-time. Afterward, two numerical examples are calculated and simulated to illustrate the effectiveness and feasibility of proposed strategies. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of exponential stability and stabilization for a class of delayed distributed parameter systems, which is modeled by partial integro-differential equations (PIDEs). By employing the vector-valued Wirtinger's inequality, the sufficient condition of exponential stability of the PIDE system with a given decay rate is investigated. The condition is presented by linear matrix inequality (LMIs). After that, we develop a spatial proportional-integral-derivative state-feedback controller that ensures the exponential stabilization of the PIDE system in terms of LMIs. Finally, numerical examples are presented to verify the effectiveness of the proposed theoretical results. [ABSTRACT FROM AUTHOR]

This paper mainly addressed the stability analysis and the estimation of domain of attraction for the endemic equilibrium of a class of susceptible-exposed-infected-quarantine epidemic models. Firstly, we discuss the global stability of the disease-free equilibrium and the local stability of the endemic equilibrium in the feasible region D of the epidemic model, respectively. Secondly, we use a geometric approach to investigate the global stability of the endemic equilibrium in a positive invariant region $$D_s(\subset D)$$ . Furthermore, we estimates the domain of attraction for the endemic equilibrium via sum of squares optimization method, and obtain the optimal estimation by solving an semidefinite programming problem with sum of squares polynomial constraints. Finally, numerical simulation is examined to demonstrate the feasibility and effectiveness of the research results. [ABSTRACT FROM AUTHOR]

This paper investigates the synchronization of multiple chaotic systems with unknown parameters using adaptive control method, and two kinds of different synchronization modes are considered here. One is that more response systems synchronize with one drive system, and the other is the ring transmission synchronization, which guarantees that all chaotic systems can synchronize with each other. The definition of adaptive synchronization of multiple chaotic systems with unknown parameters is given, and then based on the idea of adaptive control method, adaptive laws are derived to estimate the unknown parameters, and nonlinear adaptive controllers are developed to ensure the asymptotical stability of two classes of error systems. Finally, simulation results are presented to verify the effectiveness of proposed synchronization schemes. [ABSTRACT FROM AUTHOR]

In this paper, we study the synchronization problem for switched complex networks with delayed coupling via semi-periodically intermittent control technique and a mode-dependent average dwell time method. The mathematical model of switched complex networks is established, and the networks switch among a finite number of subnetworks in accordance with a switching rule. By applying multiple Lyapunov function method and the mode-dependent average dwell time (MDADT) approach, less conservative synchronization criteria are derived based on a sequence of solvable linear matrix inequalities. Particularly, the conventional synchronization conditions are improved by using semi-periodically intermittent control and MDADT approach. Moreover, delayed coupling may affect the stability of the switched complex networks. In this paper, novel synchronization criteria are derived to deal with the relations between time delay and other parameters appropriately. Finally, a numerical example is provided to demonstrate the effectiveness of the derived theoretical results. [ABSTRACT FROM AUTHOR]

Lanchester equations and their extensions are widely used to calculate attrition in warfare models. The current paper addresses the warfare command decision-making problem for winning when the total combats capability of the attacking side is not superior to that of the defending side. For this problem, the corresponding warfare command stratagems, which can transform the battlefield situation, are proposed and analyzed quantitatively by considering the influence of the warfare information factor. The application examples in military conflicts show the feasibility and effectiveness of the proposed model and the warfare command stratagems for winning. The research results may provide a theoretical reference for warfare command decision making. [ABSTRACT FROM AUTHOR]