This paper studies the problem of event-triggered and self-triggered H ∞ controls for uncertain switched linear systems with exogenous disturbances whose magnitude is bounded by the system state's norm. With the proposed schemes, the control task is carried out only when the triggering condition is met. That leads to changing and adaptive interexecution intervals and can further reduce the system resource costs to a certain extent. Moreover, to ensure the H ∞ control performance of the event-triggered switched system, a proof which makes certain that the occurrence of Zeno problem can be prevented is first provided. Then, by adopting the average dwell time method, a set of sufficient conditions for H ∞ performance analysis is developed. Subsequently, the codesign of controller gains and event-triggering schemes is provided. On the basis of the eventtriggered control, a solution to the self-triggered control problem is then presented. It can only utilize the current sampled data to predict the next triggered instant. Finally, in order to test the effectiveness of the proposed methods, numerical simulations are performed.
Modern atmosphere pressure interface (API) enables high-efficiency coupling between mass analyzer in high vacuum and atmosphere ionization sources such as electrospray ionization (ESI) source. The design of API is one of the key factors that influence the final performance of the electrospray ionization mass spectrometer. For evaluating and improving the interface structure, numerical modeling of particle trajectories has been widely adopted. However, in current studies, the simulation can only be processed in a discrete manner, and the critical mechanism of droplet-to-ion transformation is hardly involved. Here we propose a comprehensive and consecutive ion formation modeling method of ESI in API. In this method, not the sheer particle trajectory, but the evolution of droplets and the offspring of gaseous ions are introduced instead. And, for the first time, the dynamic droplet-to-ion transformation process in API of ESI-MS is visualized. Both the numerical and experimental results indicate that this study is instructive in improving the analytical performance of mass spectrometry and provides a better understanding of the ion evolution mechanism at both microscopic and statistical levels. And further, this study proposed a way for mass spectrometer structure optimization and ion source parameter adjustment in new aspects.
This article is concerned with the neural network (NN)-based event-triggered control problem for discrete-time networked Markov jump systems with hybrid cyberattacks and unmeasured states. The event-triggered mechanism (ETM) is used to reduce the communication load, and a Luenberger observer is introduced to estimate the unmeasured states. Two kinds of cyberattacks, denial-of-service (DoS) attacks and deception attacks, are investigated due to the vulnerability of cyberlayer. For the sake of mitigating the impact of these two types of cyberattacks on system performance, the ETM under DoS jamming attacks is discussed first, and a new estimation of such mechanism is given. Then, the NN technique is applied to approximate the injected false information. Some sufficient conditions are derived to guarantee the boundedness of the closed-loop system, and the observer and controller gains are presented by solving a set of matrix inequalities. The effectiveness of the presented control method is demonstrated by a numerical example.
The security control issue of nonlinear networked systems is considered in this article on the basis of interval type-2 fuzzy modeling strategy. For avoiding communication congestion, a stochastic scheduling strategy called Markovian communication protocol is introduced to coordinate the sensor transmission order. An asynchronous observer is designed for estimating the unmeasured states via the hidden Markov model. In addition, a more comprehensive scenario on deception attack is considered, in which attacks occur both in the sensor–observer and controller–actuator communication channels with different types of deception signals. In view of slack matrix approach and stochastic analysis technique, some sufficient conditions for ensuring the ultimately boundedness of the resulting closed-loop system are obtained. In the end, simulations show the validity of the proposed protocol-based fuzzy control method.
The relationship between China and Australia has maintained a trend of fluctuating development for a long period since the establishment of diplomatic ties. However, around 2017, Australia gradually adopted negative policies towards China, and the relationship between the two countries cooled down rapidly, with no obvious easing trend. Based on the Multiple Stream Framework, this paper attempts to use the China5G case to analyze the factors contributing to Australia's negative foreign policy toward China. The paper argues that the definition of problems by the top governmental officials and the urgency of the problem mutually determine whether the final resolution is negative or positive toward a country; that the complexity of domestic political party structure and electoral politics imply the preference for national policy; and that the lead of public opinion, as well as the government's political intention to maintain the rule of legality, are the key factors affecting the policy orientation. This analysis aims to better understand the deep connotation of the relationship between China and Australia and provides a thinking path for improving relations between the two countries. It also refers to analyzing the attitudes towards China's rise from other countries in the Asia-Pacific region.
In the construction of smart city, this paper proposes a new waterlogging measurement mode: multiple small sensors are used as waterlogging information collection terminals, LoRa technology forms a wide area information network, STM32 series microcontroller and LoRa technology feed back the waterlogging terminal information to the information processing terminals. Digital mapping technology to get an intuitive map of waterlogging conditions, Through digital map technology, intuitive waterlogging map can be obtained, and the water level of each point can be networked to serve waterlogging prevention and control in smart cities in a more specific and accurate way.
In this paper, the event-triggered active disturbance rejection control (ADRC) is first addressed for a class of uncertain lower triangular stochastic systems driven by bounded noise and colored noise. The event-triggered extended state observer (ESO) and ADRC controller are designed, where two respective event-triggering mechanisms with a fixed positive lower bound for the inter-execution times for every sample path solution of the stochastic systems are proposed. The stochastic total disturbance representing the coupling of nonlinear unmodeled dynamics, external deterministic disturbance, bounded noise, and colored noise is estimated in real time by the event-triggered ESO and compensated in the event-triggered feedback loop. Both the mean square and almost surely practical convergence of the closed-loop systems is shown with rigorous theoretical analysis. Finally, some numerical simulations are presented to validate the theoretical results.
The stability issue of stochastic hybrid systems against energy-constrained denial-of-service (DoS) attacks is investigated in this article. A sampled-data-based Round-Robin protocol, which sends measurement data cyclically according to the predetermined transmission sequence, is introduced to avoid communication network congestion. Additionally, a new switched time-delay stochastic closed-loop system with an unstable subsystem is established by discussing the effect of DoS attacks. Then, the stability of the closed-loop system is discussed in light of the piecewise Lyapunov–Krasovskii functional method and stochastic analysis technique. Finally, two examples are included to illustrate the correctness and applicability of the proposed method.
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