In this paper, the nonlinear disturbance observer-based control (NDOBC) scheme is proposed for a class of discrete-time stochastic systems with multiple heterogenous disturbances, which include the non-harmonic disturbance and a sequence of random vectors. A nonlinear disturbance observer (NDO) is designed to estimate the non-harmonic disturbance, then the NDOBC scheme is proposed by combining DOBC with [Formula: see text] control, such that the composite system can achieves asymptotically mean-square bounded and asymptotically mean-square stable in different conditions. Finally, simulation results show the effectiveness of the proposed method.

The finite-time anti-disturbance control problem is studied for systems with multiple heterogeneous disturbances, which include the disturbance with partially known information and the external disturbance. A disturbance observer is designed to online estimate the disturbance with partially known information. Based on this, a disturbance observer–based finite-time control (DOBFTC) scheme is presented by combining disturbance observer–based control (DOBC) with finite-time control method to guarantee that the composite system is globally finite-time stable. Two simulation examples including a numerical example and a doubly fed induction generators (DFIG) system are given to show the effectiveness of the proposed method compared with the existing schemes.

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Based on the PSM (Propensity Score Matching) approach, this paper presents a rigorous empirical argument to illustrate the statistical relationship between the audit background of the Big Four accounting firms and the quality of corporate accounting information, using a sample of all listed companies in Shanghai and Shenzhen A-shares from 2011 to 2020. This paper finds that after selecting the control and treatment groups under the PSM approach and solving the model endogeneity problem, the information quality of companies with the audit background of the Big Four accounting firms is significantly better than that of companies audited by ordinary accounting firms.