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In order to save the usage of system resources and adapt the variation of plant state, this study first proposes a novel stochastic-sampling-based adaptive event-triggered scheme (AETS). Second, in the framework of time-delay systems, the closed-loop control system is modelled as a class of delayed stochastic systems where time-delay is distributed in some intervals with probability. Then, by employing stochastic analysis tool and Lyapunov stability theory, a stability criterion for this class of delayed stochastic systems is established to ensure that the system possesses stochastically asymptotic stability with an H ∞ disturbance attenuation performance. Also, a co-design of parameter matrices of the state-feedback controller and the stochastic-sampling-based AETS is implemented. Third, based on the obtained co-design condition, a convex optimisation algorithm for the tradeoffs between disturbance attenuation performance and resource utilisation of the closed-loop control system is further developed. Finally, the effectiveness and feasibility of the proposed control strategy are illustrated by two numerical examples of adaptive event-triggered control for networked control systems under stochastic sampling.

Ultrafast laser micromachining of crystalline silicon carbide (SiC) has great perspectives in aerospace industry and integrated circuit technique. In this report, we present a study of femtosecond laser nanostructuring on the surface of an n-type 4H-SiC single crystal. Except for uniform nanogratings, new types of large-area periodic structures including nanoparticle array and nanoparticle-nanograting hybrid structures were induced on the surface of 4H-SiC by scanning irradiation. The effects of pulse energy, scan speed, and the polarization direction on the morphology and periodicity of nanogratings were systematically explored. The proper parameter window for nanograting formation in pulse energy-scan speed landscape is depicted. Both the uniformity and the periodicity of the induced nanogratings are polarization dependent. A planar light attenuator for linear polarized light was demonstrated by aligning the nanogratings. The transition between different large-area periodic structures is achieved by simultaneous control of pulse energy and scan interval using a cross scan strategy. These results are expected to open up an avenue to create and manipulate periodic nanostructures on SiC crystals for photonic applications.

This paper investigates the distributed consensus problem for heterogeneous multi-agent systems via event-triggered scheme. To alleviate the communication burden, a distributed event-triggered consensus algorithm using an open-loop estimate and neighboring information is proposed. In the proposed event-triggered scheme, the control input of each agent is dependent on the estimate and information at discrete instants. Firstly, the novel event-triggered consensus algorithm is proposed for fixed topology, which involves the discrete communication between neighboring agents. Then, for the switching topology, the triggering condition is proposed by virtue of a topology-dependent dwell time approach. Further, the corresponding consensus procedures are given. Finally, the effectiveness of the proposed scheme is illustrated by numerical results.

This paper is concerned with the resilient event-triggered control (RETC) for cyber-physical systems (CPSs) under stochastic sampling and denial-of-service (DoS) attacks. Firstly, considering the effects of the stochastic sampling and the energy-constrained, aperiodic DoS attacks, an attack-resilient event-triggered scheme (ETS) under stochastic sampling is proposed to reduce the usage of system resources. Secondly, a class of delayed switched stochastic system model where time-delay is distributed in some intervals with probability is established for closed-loop system. Then, by using the Lyapunov stability theory, the switched systems theory and the stochastic analysis tool, the co-design algorithm which used to jointly design the event-trigger and state-feedback controller is developed. Finally, a numerical example on the secure control for a satellite control system is provided to demonstrate the effectiveness of the proposed control scheme.

The additional threshold of a mixed event-triggering mechanism (ETM) makes it impossible to guarantee the requirement of asymptotic stability. As a consequence, it is necessary to investigate input-to-state practically stable (ISpS) which is a mild stability property. In this study, the authors firstly model the closed-loop event-triggered control system as a delayed linear parameter-varying (LPV) systems with a mixed ETM and parameter uncertainty. Then, a co-design condition in a sense of ISpS of controller gain and trigger parameters for the delayed LPV systems is obtained by employing the parameter-dependent Lyapunov–Krasovskii functionals and congruent transformation method. Moreover, based on the obtained co-design condition in a sense of ISpS, an optimisation algorithm for the tradeoffs between resource utilisation and robustness of the closed-loop system is further proposed. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed method.

This paper investigates the adaptive-event-triggered-control (AETC) for networked control systems (NCSs). Firstly, a novel adaptive event-triggered scheme (AETS) under stochastic sampling is proposed to reduce the unnecessary data communication between sensor and controller, to adapt the variation of the plant states, and to improve the flexibility of selection of sampling period. Secondly, in the framework of time-delay systems, the closed-loop control system with an AETS under stochastic sampling is modelled as an interval time-varying delayed system. Then, by employing Lyapunov stability theory, some conditions are obtained to determine that closed-loop control system is stochastically asymptotically stable with $H_{\infty}$ disturbance attenuation performance and to carry out the co-design of parameter matrices of AETS and controller. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed scheme.

This study is concerned with stability analysis for Takagi–Sugeno (T–S) fuzzy systems with time-varying delay. By applying the idea of scalar function and augmented vectors, dealing with the positivity of a functional, a novel simple Lyapunov–Krasovskii functional is established. Then, fuzzy-weighting dependent matrices and the reciprocally convex approach are introduced to deal with two integral parts, convex analysis approach is used to solve the useful terms (which are ignored in previous methods), with the above methods some less conservative stability criteria is obtained. Finally, three numerical examples are provided to show the effectiveness and improvements of the proposed conditions.

Manipulation of femtosecond laser induced microstructures in glass by tuning the laser polarization has great potential in optics. Here we report two different polarization-dependent microstructures and their evolution with pulse repetition rate in an aluminosilicate glass induced by femtosecond laser irradiation. A V-shaped crack oriented parallel to the laser polarization plane is induced at the bottom of modified regions by pulses operated at 200 kHz, 1030 nm, and 300 fs. Further increasing the pulse repetition rate to 500 kHz leads to the formation of a dumbbell-shaped structure, which is elongated perpendicularly to the laser polarization, at the top of the modified region. The size of the coloration area and the dumbbell-shaped structure can be controlled by tuning the pulse duration. Further investigation indicates that higher numerical apertures are in favor of the presence of the polarization effects in femtosecond laser irradiation. The possible mechanism responsible for the formation of the two microstructures is discussed. These results could be helpful for understanding of ultrafast laser interaction with glass.

In the paper, the problem of stability is addressed for a class of time varying delay T-S fuzzy systems via the reciprocally convex approach. By using some new Lyapunov-Krosovskii functions, nonuniform time delay dividing method and a reciprocally convex approach, new delay-derivative-dependent stability criterion is derived with less conservativeness, compared with some exist results. A numerical example is given to demonstrate the effectiveness and merit of the proposed technique.