1,723,187 research outputs found
L’insediamento neolitico di Puisteris –Mogoro (OR): nuovi dati dallo scavo di una “sacca” in località Serra Neula
No full textLa necropoli di Othoca
No full textArticolo di sintesi sulla necropoli di Othoca e sugli ultimi scavi ivi condotti
La necropoli di Othoca (Santa Giusta - OR): campagne di scavo 1994-95 e 1997-98. Note preliminari
No full textRelazione preliminare degli scavi effettuati nella necropoli fenicio-punica e romana di Othoca negli anni novanta. Si presentano le tombe più significative e i rispettivi corredi
A novel finite-time first-order sliding-mode unknown input observer with certain fixed-time convergence characteristics
No full textFor uncertain linear system subjected to uniformly bounded unknown inputs it is presented a novel finite-time unknown input first-order sliding-mode observer. The strategy involves the design of a pair of quadratically stable first-order sliding-mode observers, aimed to guarantee the robustness to non-smooth unknown inputs and the finite-time convergence to zero of the output estimation errors. Then, the exact estimation of the unmeasured states is achieved in a fixed-time since the sliding motion is established through the design of an auxiliary output consisting of a delayed linear-combination of the estimations provided by the above-mentioned pair of observers. To confirm the effectiveness of the proposed scheme, along with a sketch of the proof of its convergence characteristics, a detailed numerical comparison analysis with the existing first-order sliding-mode competitor observers is illustrated
Chattering avoidance by second order sliding mode control
No full textRelying on the possibility of generating a second-order sliding motion by using, as control, the first derivative of the control signal instead of the actual control, a new solution to the problem of chattering elimination in variable structure control (VSC) is presented. Such a solution, inspired by the classical bang-bang optimal control strategy, is first depicted and expressed in terms of a control algorithm by introducing a suitable auxiliary problem involving a second-order uncertain system with unavailable velocity. Then, the applicability of the algorithm is extended, via suitable modifications, to the case of nonlinear systems with uncertainties of more general types. The proposed algorithm does not require the use of observers and differential inequalities and can be applied in practice by exploiting such commercial components as peak detectors or other approximated methods to evaluate the change of the sign of the derivative of the quantity accounting for the distance to the sliding manifold
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