Dissipative Analysis and Synthesis of Control for TS Fuzzy Markovian Jump Neutral Systems

This paper is focused on stochastic stability and strictly dissipative control design for a class of Takagi-Sugeno (TS) fuzzy neutral time delayed control systems with Markovian jumps. The main aim of this paper is to design a strictly dissipative controller such that the closed-loop TS fuzzy control system is stochastically stable, and also the disturbance rejection attenuation is obtained to a given level by means of the H∞ performance index. Intensive analysis is carried out to obtain sufficient conditions for the existence of desired dissipative controller which ensures both the stochastic stability and the strictly dissipative performance. The main advantage of the proposed technique is that it is possible to obtain the dissipative controller with less control effort and also, as special cases, robust H∞ control with the prescribed H∞ performance under given constraints and passivity control can be obtained for the considered systems. Also, the existence condition of the fuzzy dissipative controller can be obtained in terms of linear matrix inequalities. Finally, a practical example based on truck-trailer model is provided to demonstrate the effectiveness and feasibility of the proposed design technique

Mitigation of vortex-induced vibration lock-in using time-delay closed-loop control

We investigate the closed-loop control of a circular cylinder showing lock-in phenomena due to vortex-induced vibrations (VIV). The control action was implemented by a sampled-data proportional-integral-derivative (PID) controller to suppress the large amplitudes due to lock-in. The controller was first applied to a linearized system to observe its stability characteristics based on the eigenvalues of the system. Another method was also proposed, which employs a novel, time-dependent Lyapunov function that is positive definite at sampling times but not necessarily between the sampling times. A new set of sufficient conditions in terms of linear matrix inequalities is derived to obtain the sampled-data PID control gains for the VIV system. The PID controller tuned with these gains for various delays was applied to control the nonlinear responses of the circular cylinder during the lock-in. The results showed that the PID controller significantly reduced the rise in lock-in amplitude compared to only proportional control and for certain delays was able to completely mitigate the effects of lock-in. It was also observed that for delays ranging from 0.1 to 0.14 s, the nonlinear system was destabilized with increasing proportional gains as indicated by the eigenvalue analysis of the linearized system. Even under such situations, properly tuned integral and derivative gains could significantly reduce the amplitude rise otherwise observed due to lock-in of the uncontrolled system. Finally, an on-off control scheme was also proposed, which, if optimized properly, can restrict the lock-in amplitude to some prescribed limit by only using the control for some fraction of the total operational time. Thus, it can potentially save control power

Dissipative based adaptive reliable sampled-data control of time-varying delay systems

This paper is concerned with the problem of dissipative based adaptive reliable controller for a class of time delay systems subject to actuator failures and time-varying sampling with a known upper bound on the sampling intervals. By constructing a proper Lyapunov-Krasovskii functional which fully uses the available information about the actual sampling pattern and time delays, a new set of sufficient conditions is derived to obtain the required result. Then, a dissipative based adaptive sampled-data controller is designed such that the resulting closed-loop system is reliable in the sense that it is asymptotically stable and has the prescribed dissipative performance under given constraints. The existence condition of the desired dissipative based adaptive reliable sampled-data controller is obtained in terms of linear matrix inequalities. Further, the performance of the proposed controller is implemented on a liquid propellant rocket motor with a pressure feeding system model. The simulation results show the effectiveness and better performance of the proposed adaptive reliable sampled-data controller over conventional reliable controller

Palladium-catalysed regioselective aroylation and acetoxylation of 3,5-diarylisoxazole via ortho C–H functionalisations

The higher directing ability of N over O in 3,5-diarylisoxazole is demonstrated during the construction of C–C and C–O bonds. Out of the four ortho sp² C–Hs and one internal sp² C–H in 3,5-diarylisoxazoles, regioselective aroylation and acetoxylation take place at one of the ortho-C–Hs proximal to the N atom using Pd(OAc)₂ as the catalyst in the presence of suitable oxidants and solvents