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In this paper, stabilization of a nonlinear bilateral teleoperation system with time delays and actuator saturation is investigated via active disturbance rejection control (ADRC). An linear extended state observer is introduced to deal with the lumped system uncertainties. Lyapunov functions are given to prove the stabilization of the closed-loop bilateral teleoperation system. Two Phantom Premium 1.5 HighForce (HF) robot manipulators are used in experiments to demonstrate the effectiveness of the proposed method in this paper.

BackgroundIn social networks, trust is a complex social network. Participants in online social networks want to share information and experiences with as many reliable users as possible. However, the modeling of trust is complicated and application dependent. Modeling trust needs to consider interaction history, recommendation, user behaviors and so on. Therefore, modeling trust is an important focus for online social networks.MethodsWe propose a game theory-based trust measurement model for social networks. The trust degree is calculated from three aspects, service reliability, feedback effectiveness, recommendation credibility, to get more accurate result. In addition, to alleviate the free-riding problem, we propose a game theory-based punishment mechanism for specific trust and global trust, respectively.Results and conclusionsWe prove that the proposed trust measurement model is effective. The free-riding problem can be resolved effectively through adding the proposed punishment mechanism.

In this paper, adaptive finite-time control is addressed for a class of high-order nonlinear systems with mismatched disturbances. An adaptive finite-time controller is designed in which variable gains are adjusted to ensure finite-time stabilization for the closed-loop system. Chattering is reduced by a designed adaptive sliding mode observer which is also used to deal with the mismatched disturbances in finite time. The proposed adaptive finite-time control method avoids calculating derivative repeatedly of traditional backstepping methods and reduces computational burden effectively. Three numerical examples are given to illustrate the effectiveness of the proposed method. KEYWORDS adaptive control, finite-time control, high-order nonlinear systems, mismatched disturbances, sliding mode observers 1 1296

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Land border tourism in China serves as a pillar industry in local economic development and is an important sector for international cooperation. This paper aims to fill the gap in the spatial pattern of land border tourism resources in China using geographical information systems (GIS) and spatial statistical methods. The pattern was analyzed from the aspects of numerical features, spatial variance, and spatial association at different spatial scales. The results show that 3341 land border tourism resources in China reveal significant clusters and outliers at both the prefectural and county scales, offering useful information for the management of tourism resources. Physical factors, cultural diversity, regional policies, the relationships between neighboring countries, and public facilities are shown to be the main factors influencing the patterns. It is suggested that the government should adjust its management policies based on the characteristics of local resources, conduct combinatorial development of different types of resources, strengthen the cooperation domestically and internationally, improve public facilities, and protect the local environment and ethnic culture.

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