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International audience; We experimentally studied sequential {101-2} twinning in rolled pure titanium at room temperature and identified a new sequential twinning mechanism, i.e., {101-2} (T) extension twin stimulated by the twin-twin junction of two primary {1121} extension twins T and T, which holds a certain relation T T→T. Schmid factor analysis, as the local stress is taken into account, is able to determine the position of sequential twin variant, but cannot determine the twin variant. Displacement gradient accommodation is used to determine the twin variant. The well-known secondary {1012} (T) extension twins in primary {1122} (C) contraction twins (referred to as C → T double twinning) are also analyzed according to a generalized Schmid factor analysis. Displacement gradient accommodation and twin nucleation based on dislocations dissociation only work well for the most active twin variants, but cannot address other phenomena associated with C → T double twinning. For rarely activated twin variants, displacement gradient accommodation was not satisfied.

There are some problems that disturb researchers and developers working on multidimensional signal processing as computer senses. One of these problems is to find more reasonable characteristic parameters for speeches, letters, maps and senses. As is known, LPC-CEP coefficients as the main parameters drawing from signals are widely used and, unfortunately, in the parameter space of which some signals cannot be distinguished. Moreover LPC-CEP coefficients are obtained based on the linear AR (auto-regression) model, so assumption of certain stability for these signals is necessary and the order of the AR model cannot help to simplify the model from ARMA(p,q). But we must address the nonlinear signal to deal with the above information. Finally, the space possess too high a multidimensional number to calculate in time. To avoid these troubles and to strengthen the ability of the models, we study a type of nonlinear stochastic models, AR(p)-MA(q).