Publications

This paper is concerned with the robust absolute stability analysis problem for a class of uncertain time-delay systems with nonlinearities satisfying a given sector condition. Based on the Lyapunov stability theory and the linear matrix inequality (LMI) approach, a delay-dependent sufficient condition for the robust absolute stability is derived and is expressed as the feasibility problem of a certain LMI system. A maximum upper bound of the allowable delay is obtained by solving a convex optimization problem. Finally, a numerical example is given to illustrate the proposed results.

This paper deals with master–slave synchronization for Lur'e systems subject to a more general sector condition by using time delay feedback control. A new Lyapunov–Krasovskii functional and a new Lur'e–Postnikov Lyapunov functional are proposed to obtain some new delay-dependent synchronization criteria, which are formulated in the form of linear matrix inequalities (LMIs). These criteria cover some existing results as their special cases. An example shows that the result derived in this paper significantly improves some existing ones.

We study the asymptotics of complete Kähler-Einstein metrics on strictly pseudoconvex domains in $$\mathbb {C}^n$$ and derive a convergence theorem fo

This paper is concerned with stability of linear neutral systems. Firstly, a new approach, a delay decomposition approach, is proposed to deal with the stability issue. The idea of the approach is that the delay interval is uniformly divided into N segments with N a positive integer, and a proper Lyapunov-Krasovskii functional is chosen with different weighted matrices corresponding to different segments in the Lyapunov-Krasovskii functional. Secondly, based on the delay decomposition approach, some new delay-dependent stability criteria for linear neutral systems are derived. These criteria are much less conservative and include some existing results as their special cases. Finally, numerical examples show that significant improvement using the delay decomposition approach is achieved over some existing method even for coarse delay decomposition.

Offshore platforms are widely used to explore, drill, produce, storage, and transport ocean resources and are usually subject to environmental loading, suc

This chapter is concerned with the distributed optimizationDistributed optimization of a multi-agent system with network connectivity preservationConnectivity preservation. In order to realize cooperative interactions, a connected network is the prerequisite for...

In high efficiency video coding (HEVC) standard, residuals are partitioned into variable-size transform units, and integer cosine transforms (ICTs) of order-4, 8, 16, and 32 are adopted to optimize the coding performance. Order-64 ICT is not used due to its high complexity and limited gain in general coding applications. This paper proposes a set of low-complexity ICTs (LCICTs), from order-8 to order-64, which have fully factorizable structures. LCICTs achieve similar coding performance as the state-of-art methods on HEVC Test Model 13 while requiring lower complexity, e.g., 71% fewer multiplications than the partially factorizable ICTs in the order-64 case. Moreover, we find that order-64 ICTs achieve around 1% average bitrate reduction at high quantization parameters.

This paper deals with the stability problem for a class of linear neutral delaydifferential systems. The time delay is assumed constant and known. Delaydependent criteria are derived. The criteria are given in the form of linear matrix inequalities which are easy to use when checking the stability of the systems considered. Numerical examples indicate significant improvements over some existing results.

This paper investigates the decentralized control for a large-scale system with an IP-based communication network. The decentralized controller design specifically takes the nonuniform communication-delay-distribution characteristic of the IP-based communication network into account. First, a networked decentralized control modeling for the large-scale system is proposed. The two main points are: 1) a decentralized controller is designed, which does not depend on the full-order state of the system and 2) the nonuniform communication-delay-distribution characteristic of the IP-based communication network is fully considered in the controller design. Second, if the probability distribution of communication delay is known a priori in the design process, sufficient stability and stabilization conditions for the networked large-scale system are derived in terms of linear matrix inequalities. It shows that, the solvability of the design depends not only on the probability distribution of the communication delay but also on the network topology. Finally, the design method is applied to two pendulums coupled by a spring and a quadruple-tank process. Simulation results demonstrate the effectiveness of the proposed method.

A version of the singular Yamabe problem in smooth domains in a closed manifold yields complete conformal metrics with negative constant scalar curvatures. In this paper, we study the blow-up phenomena of Ricci curvatures of these metrics on domains whose boundary is close to a certain limit set of a lower dimension. We will characterize the blow-up set according to the Yamabe invariant of the underlying manifold. In particular, we will prove that all points in the lower dimension part of the limit set belong to the blow-up set on manifolds not conformally equivalent to the standard sphere and that all but one point in the lower dimension part of the limit set belong to the blow-up set on manifolds conformally equivalent to the standard sphere. In certain cases, the blow-up set can be the entire manifold. We will demonstrate by examples that these results are optimal.

This paper is concerned with event-triggered consensus of general linear multiagent systems (MASs) in leaderless and leader-following networks, respectively, in the framework of adaptive control. A distributed dynamic event-triggered strategy is first proposed, in which an auxiliary parameter is introduced for each agent to regulate its threshold dynamically. The time-varying threshold ensures less triggering instants, compared with the traditional static one. Then under the proposed event-triggered strategy, a distributed adaptive consensus protocol is formed including the updating law of the coupling strength for each agent. Some criteria are derived to guarantee leaderless or leader-following consensus for MASs with general linear dynamics, respectively. Moreover, it is proved that the triggering time sequences do not exhibit Zeno behavior. Finally, the effectiveness of the proposed dynamic event-triggered control mechanism combined with adaptive control is validated by two examples.

Connected automated vehicles (CAVs) serve as a promising enabler for future intelligent transportation systems because of their capabilities in improving traffic efficiency and driving safety, and reducing fuel consumption and vehicle emissions. A fundamental issue in CAVs is platooning control that empowers a convoy of CAVs to be cooperatively maneuvered with desired longitudinal spacings and identical velocities on roads. This paper addresses the issue of resilient and safe platooning control of CAVs subject to intermittent denial-of-service (DoS) attacks that disrupt vehicle-to-vehicle communications. First, a heterogeneous and uncertain vehicle longitudinal dynamic model is presented to accommodate a variety of uncertainties, including diverse vehicle masses and engine inertial delays, unknown and nonlinear resistance forces, and a dynamic platoon leader. Then, a resilient and safe distributed longitudinal platooning control law is constructed with an aim to preserve simultaneous individual vehicle stability, attack resilience, platoon safety and scalability. Furthermore, a numerically efficient offline design algorithm for determining the desired platoon control law is developed, under which the platoon resilience against DoS attacks can be maximized but the anticipated stability, safety and scalability requirements remain preserved. Finally, extensive numerical experiments are provided to substantiate the efficacy of the proposed platooning method.

This paper is concerned with the stability of linear systems with interval time-varying delays arising from networked control systems (NCSs). The Jensen integral inequality is first generalized into a new inequality to overcome the limitation of applications. Then a novel delay-dependent stability criterion is derived by combining the generalized Jensen integral inequality and the convex combination technique. It is proven theoretically that the stability criterion is less conservative than some existing results, which is confirmed by two numerical examples.

This paper is concerned with the distributed guaranteed estimation for tracking two interacting mobile targets over a multi-sensor network in the presence of unknown-but-bounded noises and various adversarial attacks. First, a heterogeneous sensor network framework in terms of two distinct groups of sensors is employed to monitor the two targets. Each sensor in either group possesses different sensing, processing and communicating capabilities, thereby leading to distinct communication topologies among intra- and inter-group sensors. Second, a unified attack model is established to skillfully accommodate multiple adversarial attacks including node manipulation attacks and deception attacks. Third, two different groups of distributed consensus-based estimators are delicately constructed to deal with the network heterogeneity. Criteria for designing the desired estimators are then derived such that the true states of the two maneuvering targets are guaranteed to be enclosed by the calculated estimate ellipsoids at each time step regardless of the noises and attacks. Furthermore, two tractable optimization algorithms, in both single- and two-target tracking cases, are applied to recursively calculate the smallest possible ellipsoidal estimate sets. Finally, numerical verification of distributed two-vehicle tracking is carried out to demonstrate the effectiveness and applicability of the obtained results.

In this article, the problem of consensus control is investigated for a class of multiagent systems (MASs) with both stochastic noises and nonidentical exogenous disturbances. The signal transmission among agents is implemented through a digital communication network subject to both uniform quantization and round-robin protocol as a reflection of network constraints. The consensus strategy is designed by adopting the estimates of the relative states of the agent to its neighbors, which renders the distributed nature of the controller. A new consensus concept, namely, quasiconsensus in probability, is employed to evaluate the state response of the agents to the stochastic noises, the exogenous disturbances, and the quantization error. An augmented system is first formed that relies on the deviations of the individual state from the average state, the observer error of the relative state, as well as the relative measurement output. Based on the augmented model, an analysis approach on dynamical behaviors is developed to facilitate the consensus analysis of MASs by means of the switching Lyapunov function technique and the stochastic analysis methods. Then, the existence condition and the explicit expression of the time-varying gain matrices are proposed for the expected controller by resorting to the feasibility of several matrix inequalities. Numerical simulation results are presented to demonstrate the applicability of the theoretical results.

This paper is concerned with quantitative analysis and synthesis for continuous-time networked control systems (NCSs) with packet dropouts and interval time-varying sampling period. A new packet dropout separation method is proposed to separate packet dropouts from the sum of network-induced delay and packet dropouts, and an interval time-varying sampling period approach is presented to model the variation of sampling period. Then, a novel packet dropout decomposition based Lyapunov functional is constructed, and the quantitative relationships between packet dropout probability and stability and stabilization of NCSs are established. A numerical example is given to illustrate the merits and effectiveness of the proposed methods.