This paper deals with the problem of robust fault detection for discrete-time switched systems with state delays under arbitrary switching signal. The fault detection filter is used as the residual generator, in which the filter parameters are dependent on the system mode. Attention is focused on designing the robust fault detection filter such that, for unknown inputs, control inputs and model uncertainties, the estimation error between the residuals and the faults is minimized. The problem of robust fault detection is converted into an H∞ filtering problem. By switched Lyapunov functional approach, a sufficient condition for the solvability of this problem is established in terms of linear matrix inequalities (LMIs). A numerical example is provided to demonstrate the effectiveness of the proposed method.

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A novel surface modification method, namely the surface nanocrystallization technology, is introduced to enhance the anti–buckling performance of the metal cylindrical shells under axial impact loading. The effects of local nanocrystallization layouts are explored by evaluating the critical buckling loads of four local nanocrystallization layouts including the local circumferential stripes (LCS), local axial stripes (LAS), spaced latticed blocks (SLB) and oblique latticed blocks (OLB). Numercial results show that, compared to the untreated cylindrical shells, the critical buckling loads of the local nanocrystallized ones are significantly improved by the local nanocrystallization treatment. The critical buckling loads for the LAS design is improved by 80%. It is concluded that the local nanocrystallization treatment is a very promising method to design and manufacture the metal cylindrical shells with high anti-buckling performance.