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SUMMARYThis paper is concerned with delay-dependent exponential stability for stochastic Markovian jump systems with nonlinearity and time-varying delay. An improved exponential stability criterion for stochastic Markovian jump systems with nonlinearity and time-varying delay is proposed without ignoring any terms by considering the relationship among the time-varying delay, its upper bound and their difference, and using both Itô's differential formula and Lyapunov stability theory. A numerical example is given to illustrate the effectiveness and the benefits of the proposed method.

This paper focuses on mode‐dependent H∞ state‐feedback control for a class of discrete‐time Markovian jump systems (MJSs) with partial information on transition probabilities (TPs). The augmented free‐connection weighting matrices are introduced by considering the influence of partial information of TPs on discrete‐time MJSs and the disturbance input on the state vector. As a result, the less conservative stability criterion and bounded real lemma (BRL) of MJSs with partly unknown TPs are obtained. Then the sufficient conditions for designing the mode‐dependent H∞ controllers are derived in terms of linear matrix inequalities (LMIs). Numerical examples are given to illustrate the effectiveness and the merits of the proposed method.

This paper uses an improved delayed detached eddy simulation method to investigate the unsteady flow features of the high-speed trains with various cavity lengths at Re = 1.85×106. The improved delayed detached eddy simulation results are validated against the experimental data obtained during previous wind tunnel tests. The effects of cavity length on the resistance force, flow structures beneath the high-speed train and in the wake are analyzed. The results show that a longer cavity significantly increases the streamwise velocity level near the rear plates and forms a stronger impinging flow on the rear plates, and thus contributes to a higher value of resistance. Furthermore, a longer cavity decreases the pressure coefficients around the near wake region from the top of the ballast to the tail nose in the vertical direction and thereby increases the pressure drag of the high-speed train. Additionally, a longer bogie cavity is found to increase the longitudinal vortex scales in the near wake region. All these changes on the flow field bring to 5.8% and 11.5% drag increase when the bogie cavities are elongated by 20% and 40%, respectively, of the wheelbase.