The main contribution is to present stability analysis criterion for a type of norm⁃bounded uncertain perturbed discrete systems(NUPDS) with its states is subjected to a novel ellipsoidal outer approximation,which is different from the traditional bound description of general state. Based on the Lyapunov method, a delay dependent criterion and the corresponding state feedback control law, which are expressed in terms of linear matrix inequalities(LMIs) technology, are proposed to guarantee the asymptotic stability for the perturb delay systems. The solution of the LMIs can be obtained easily using existing efficient convex optimization techniques. A numerical example is given to illustrate effectiveness of the proposed method.

Engineering design revolved a lot of design data. Partial design data were described in the form of curve chart. Spiral angle coefficient curve was a typical engineering curve and had the characteristics of engineering curves. In the paper, spiral angle coefficient curve was as an example in which scanning image preprocessing, image revision, image cropping, binarization processing, mesh removing, characteristics point extracting of spiral angle coefficient curve were put forward. Furthermore, the least square method was used to fit characteristic points and accomplish digitizing of engineering curves.