Non-fragile estimation for discrete-time T-S fuzzy systems with event-triggered protocol

summary:This paper investigates the non-fragile state estimation problem for a class of discrete-time T-S fuzzy systems with time-delays and multiple missing measurements under event-triggered mechanism. First of all, the plant is subject to the time-varying delays and the stochastic disturbances. Next, a random white sequence, the element of which obeys a general probabilistic distribution defined on $[0,1]$, is utilized to formulate the occurrence of the missing measurements. Also, an event generator function is employed to regulate the transmission of data to save the precious energy. Then, a non-fragile state estimator is constructed to reflect the randomly occurring gain variations in the implementing process. By means of the Lyapunov-Krasovskii functional, the desired sufficient conditions are obtained such that the Takagi-Sugeno (T-S) fuzzy estimation error system is exponentially ultimately bounded in the mean square. And then the upper bound is minimized via the robust optimization technique and the estimator gain matrices can be calculated. Finally, a simulation example is utilized to demonstrate the effectiveness of the state estimation scheme proposed in this paper

Finite-time decentralized event-triggered feedback control for generalized neural networks with mixed interval time-varying delays and cyber-attacks

This article investigates the finite-time decentralized event-triggered feedback control problem for generalized neural networks (GNNs) with mixed interval time-varying delays and cyber-attacks. A decentralized event-triggered method reduces the network transmission load and decides whether sensor measurements should be sent out. The cyber-attacks that occur at random are described employing Bernoulli distributed variables. By the Lyapunov-Krasovskii stability theory, we apply an integral inequality with an exponential function to estimate the derivative of the Lyapunov-Krasovskii functionals (LKFs). We present new sufficient conditions in the form of linear matrix inequalities. The main objective of this research is to investigate the stochastic finite-time boundedness of GNNs with mixed interval time-varying delays and cyber-attacks by providing a decentralized event-triggered method and feedback controller. Finally, a numerical example is constructed to demonstrate the effectiveness and advantages of the provided control scheme

Discrete Time Systems

Discrete-Time Systems comprehend an important and broad research field. The consolidation of digital-based computational means in the present, pushes a technological tool into the field with a tremendous impact in areas like Control, Signal Processing, Communications, System Modelling and related Applications. This book attempts to give a scope in the wide area of Discrete-Time Systems. Their contents are grouped conveniently in sections according to significant areas, namely Filtering, Fixed and Adaptive Control Systems, Stability Problems and Miscellaneous Applications. We think that the contribution of the book enlarges the field of the Discrete-Time Systems with signification in the present state-of-the-art. Despite the vertiginous advance in the field, we also believe that the topics described here allow us also to look through some main tendencies in the next years in the research area

Biotic pump of atmospheric moisture: A conceptual model

The Biotic Pump Theory, as described by Drs. Makarieva and Gorshkov (M&G), defines the mechanism by which water vapour is transported from areas of low evaporation to areas of high evaporation, conveniently termed “donor” and “acceptor” regions, respectively, and where only the latter exhibits condensation. The implications of such a theory are critical, especially to moisture regulation of tropical rainforests, yet highly controversial. Unfortunately, most of the theory’s physics cannot be evaluated due to the lack of atmospheric observations over such areas. This study aims at building a conceptual model of the theory over the Amazon basin as to quantitatively assess the existence and determine the properties of donor and acceptor regions statistically through their respective condensation rates. The model uses the predictive capabilities of Time-Delayed Neural Networks to downscale available atmospheric observations to calculate condensation rates at a scale suited for this analysis. Validation of the downscaling model reveals monthly Mean Absolute Errors to range between 0.022 m s-1 and 2.76 m s-1 in the predictions of vertical velocity and zonal wind speed, respectively. Findings quantitatively support the existence of a biotic mechanism regulating the transport of water vapour as these clearly show the presence of donor and acceptor regions. These regions have average spatial distributions of 42% - 58%, respectively, over the whole study area and correlations are found between wind speeds and condensation rates. Mean annual condensation rate for the Amazon basin is calculated to be of 0.23E-06 mol m-3 s-1. Results also show an increase in average condensation rate (0.06E-06 mol m-3 s-1) for the last 9 years, which does not strictly adhere to M&G’s views on the impacts of deforestation on precipitation. Outcomes hence also suggest a more complex relationship between evaporation and condensation, and therefore highlight the necessity to further refine this novel theory

Fractional Order Fault Tolerant Control - A Survey

In this paper, a comprehensive review of recent advances and trends regarding Fractional Order Fault Tolerant Control (FOFTC) design is presented. This novel robust control approach has been emerging in the last decade and is still gathering great research efforts mainly because of its promising results and outcomes. The purpose of this study is to provide a useful overview for researchers interested in developing this interesting solution for plants that are subject to faults and disturbances with an obligation for a maintained performance level. Throughout the paper, the various works related to FOFTC in literature are categorized first by considering their research objective between fault detection with diagnosis and fault tolerance with accommodation, and second by considering the nature of the studied plants depending on whether they are modelized by integer order or fractional order models. One of the main drawbacks of these approaches lies in the increase in complexity associated with introducing the fractional operators, their approximation and especially during the stability analysis. A discussion on the main disadvantages and challenges that face this novel fractional order robust control research field is given in conjunction with motivations for its future development. This study provides a simulation example for the application of a FOFTC against actuator faults in a Boeing 747 civil transport aircraft is provided to illustrate the efficiency of such robust control strategies