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This paper focuses on a neural adaptive H ∞ sliding-mode control scheme for a class of uncertain nonlinear systems subject to external disturbances by the aid of adaptive dynamic programming (ADP). First, by combining the neural network (NN) approximation method with a nonlinear disturbance observer, an enhanced observer framework is developed for estimating the system uncertainties and observing the external disturbances simultaneously. Then, based on the reliable estimations provided by the enhanced observer, an adaptive sliding-mode controller is meticulously designed, which can effectively counteract the effects of the system uncertainties and the separated matched disturbances, even in the absence of prior knowledge regarding their upper bounds. While the remaining unmatched disturbances are attenuated by means of H ∞ control performance on the sliding surface. Moreover, a single critic network-based ADP algorithm is employed to learn the cost function related to the Hamilton–Jacobi–Isaacs equation, and thus, the H ∞ optimal control is obtained. An updated law for the critic NN is proposed not only to make the Nash equilibrium achieved, but also to stabilize the sliding-mode dynamics without the need for an initial stabilizing control. In addition, we analyze the uniform ultimate boundedness stability of the resultant closed-loop system via Lyapunov's method. Finally, the effectiveness of the proposed scheme is verified through simulations of a single-link robot arm and a power system. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate the ability of comment providers who were responsible for interpreting results in clinical laboratories in China and to improve the quality of interpretative comments. Methods: Basic information and interpretative comments for five cases of 1912 routine chemistry External Quality Assessment (EQA) participant laboratories were collected by web-based EQA system in May 2018. EQA organizers assigned scores to each key phrase of comments based on predetermined marking scale and calculated total scores for each participant's answer. Final scores and ranking were calculated according to scores of cases. Finally, we comprehensively analyzed the type of hospital and the professional title of participants. Results: In total, 772 clinical laboratories, 1472 participants, from different Chinese provinces submitted interpretative comments. Median scores, interquartile ranges and score ranges of the five cases were 13 (11–15, 1–20), 13 (10–16, 0–20), 15 (12–17, 0–21), 7 (5–9, −2 to 14) and 12 (10–13, −2 to 18). The final scores and ranking of participants that came from tertiary hospitals were higher than those from secondary and other hospitals; however, there were no significant differences (0.774). When grouped by professional title, we found that although no significant variability existed among senior, intermediate, junior and others (0.699), it existed between laboratory physicians and technicians, as the median final scores of the former were higher than the latter. Conclusions: Practice and quality of interpretative comments are indeed different among different laboratories and participants in China. Laboratories should train and assess the interpretative ability of personnel. EQA organizers should also improve the scoring method and establish peer assessors team through this survey. [ABSTRACT FROM AUTHOR]