This paper studies the problem of designing a robust controller for the nonlinear multi-input multi-output continuous stirred tank reactor (CSTR) in the presence of uncertainties in parameters of the process model. For this purpose, by first using the feedback linearization method, the equivalent linearized model of the CSTR is obtained. In the second step, to cope with uncertainties, two robust controllers are designed; one using H∞ mixed-sensitivity and the other using DK-iteration method. In this step, the required performance and uncertainties are expressed in terms of the suitable weight functions. Finally, the performance of the resulting feedback system is verified through numerical simulations.

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In this paper, the problem of three-dimensional (3-D) system stability is studied. In order to investigate the stability of 3-D systems, a new representation scheme is introduced based on the local state model proposed by Givone–Roesser for 3-D systems. This representation is obtained from the extended expression of the 1-D wave model proposed by Porter–Aravena. Then, according to the obtained model a new criteria for the stability of 3-D systems is stated. This criteria provides a simpler way to investigate asymptotic stability. Furthermore, an algorithm is performed to illustrate the procedure of analysing stability. Finally, some examples are performed and verified using numerical simulations in order to illustrate the given criteria for the stability.

A network stability test algorithm is proposed to check the stability of large‐scale multi‐agent systems (MAS). The method employs modelling and processing techniques for analyzing distributed communications in these systems. To model the data transactions within the network the Modified Fornasini‐Marchesini (MFM) model has been employed. In addition, a wave‐like model for processing the distributed data in the system has been proposed, which can ensure the stability of the entire system. This method is more general and less restrictive than other methods.

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