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ABSTRACT This article focuses on adaptive control of a class of non‐strict feedback nonlinear fractional order systems with input delay and unmodeled dynamics under prescribed performance constraints. Command filtering backstepping design method is employed to avoid explosion of computation. Additionally, an error compensation mechanism is established to mitigate any errors introduced by the command filter. Radial basis function neural network is utilized to approximate the nonlinear function. Auxiliary signal processing variables are introduced to handle unmodeled dynamics. To address the input delay problem, a Pade approximation technique is employed. The stability analysis of the controller is conducted using Lyapunov stability theory, ensuring that the tracking error converges within a narrow predefined performance range. Finally, simulation results are presented to demonstrate the effectiveness of the proposed controller. [ABSTRACT FROM AUTHOR]

The linear and weakly nonlinear stability of odd viscosity film with insoluble surfactants flowing down an inclined plane under a normal electric field is investigated analytically. Using the long-wave expansion method, the nonlinear evolution equations for liquid film thickness and surfactant concentration are derived. Through the normal mode analysis, the effects of surface surfactant, odd viscosity, and electric field on the neutral stability curve and the temporal growth rates are calculated to explore the linear stability of the film. Two modes, i.e., Kapitza mode and surfactant mode, are identified. Linear results show that the presence of surfactants and odd viscosity has a stabilizing effect, while electric field has a destabilizing effect on flowing of thin film. Based on the Ginsburg–Landau equation, the primary bifurcations in the phase diagram for two types of modes are investigated. The results reveal the destabilizing nature with increasing Marangoni number and viscosity ratio for surfactant mode and the stabilizing nature for Kapitza mode. [ABSTRACT FROM AUTHOR]

The linear and weakly nonlinear stability of viscoelastic film flowing down a slippery inclined plane is investigated analytically. Under the assumption of the long wave approximation, the first-order Benny equation of Oldroyd-B fluid thin film with slip condition is obtained. Through the normal mode analysis, the neutral stability curve and the temporal growth rates are calculated to explore the linear stability of the film. Linear results show that the critical Reynolds number decreases with the increase in slip length and viscoelastic parameter and that the liquid film may exhibit pure elastic instability. For the nonlinear stability analysis, both hydrodynamic instability and elastic instability are discussed. The primary bifurcations in the phase plane are identified by calculating the Landau coefficient, i.e., the unconditional stable region, the supercritical region, the subcritical region, and the explosive region. The dependence of primary bifurcation regions upon the slip length and Deborah number are studied, and the results indicate that the slip boundary and viscoelasticity destabilizes the flow. According to the Ginzburg–Landau equation, the threshold amplitude of the nonlinear equilibrium solution is analyzed as well. [ABSTRACT FROM AUTHOR]

In recent years, Sina microblog becomes an important social network platform for users to not only form personal website but share, deliver and keep interest messages via the relationships between users. However, with larger number of users in social networks, the problem of 'information overload' has been increasingly highlighted. In this case, community discovery has been the urgent requirements in microblog social networks. In this paper, a microblog community discovery algorithm based on tag correlation and interactive behaviors is presented. For the selection of exact user tags, the model of maximal marginal relevance is used and improved to enrich the variousness and novelty of user interest tags. The method of edge-similarity computation is improved to suit for microblog community discovery. Hadoop platform is applied for data process, which greatly decreases the running time of experiments. Finally, extensive experiments are provided to demonstrate the performance of proposed algorithm. The results indicate that the performance of proposed algorithm is better than that of benchmark algorithms for microblog social networks. The proposed algorithm for community discovery can identify the users belonging to multi communities or no community so that the results of community discovery are more accurate and more suitable for actual environment. [ABSTRACT FROM AUTHOR]

With the wide application of unmanned ground vehicles (UGV) in a complex environment, the research on the obstacle avoidance system has gradually become an important research part in the field of the UGV system. Aiming at the complex working environment, a sensor detection system mounted on UGV is designed and the kinematic estimation model of UGV is studied. In order to meet the obstacle avoidance requirements of UGVs in a complex environment, a fuzzy neural network obstacle avoidance algorithm based on multi-sensor information fusion is designed in this paper. MATLAB is used to simulate the obstacle avoidance algorithm. By comparing and analyzing the simulation path of UGV's obstacle avoidance motion under the navigation control of fuzzy controller and fuzzy neural network algorithm, the superiority of the proposed fuzzy neural network algorithm was verified. Finally, the superiority and reliability of the obstacle avoidance algorithm are verified through the obstacle avoidance experiment on the UGV experimental platform.