Applied Mechanics and Materials Vols. 490-491

Abstract: A novel sliding mode observer(SMO) of PMSM(permanent magnetic synchronous motor) was presented, which estimated the rotor position and angular velocity accurately.The proposed SMO substitutes a sigmoid function for the conventional signum function with a variable boundary layer which is changed according to the rotational velocity.The dependence to motor parameters and chattering effects that is commonly found in signum function using for the switching function were overcome.By combining the model of PMSM under d-q coordinate,the convergence condition of observer was deduced.The convergence was verified by the Lyapunov theory.Simulation results show that the rotor position and velocity can be observed accurately,and also has good dynamic performance and robustness.

Abstract: The chemical non-equilibrium flow of supersonic combustion ramjet (scramjet) nozzle is numerical simulated with different chemical kinetic models to research the effects on numerical results of the nozzle performance. The numerical results show that total temperature is increased due to the recombination of dissociation compositions and the combustion of the residual fuel. The effect of the combustion of the residual fuel is more obvious in this paper, and the effect to the performance of the nozzle is noticeable. The species of the compositions in the models influence the quantity of heat sending out when it get equilibrium, so the 9-species chemical kinetic models are more suitable in the simulation of the scramjet nozzle chemical non-equilibrium flows.

Abstract: In the pantograph-catenary system of electric railroads, there is friction heat between high-speed moving pantograph sliders and the contact wires, leading to a temperature increase on the contact surface. On the contact surface under the current collecting conditions, there are also contact resistance heat and arc heat produced by the current effect, leading to further temperature increase of the pantograph sliders. This paper applies finite element method to analyze the steady heat transfer and transient heat transfer of the pantograph sliders of high-speed train and studies the transient heat transfer of sliders and contact wires in actual movement. The computing results determined the temperature fluctuation range and temperature distribution when sliders and contact wires are in normal working condition.

Abstract: On the problem of mission control of the multi-UAV system in a dynamic environment, the method of Dynamic Task Allocation and Coordination (DTAC), based on the combination of market mechanism and alliance recruitment, is proposed. On the basis of the DTAC model of multi-UAV system, constructed with the application of market negotiation, the physical object of the market negotiation mechanism is substituted by that of alliance recruitment. Furthermore, the recruiter is empowered to coordinate within the alliance, which reduces the auction times and increases the efficiency of DTAC. The result of simulation shows that the method can effectively solve the problem of dynamic mission control of the Multi-UAV system.

Abstract: In this paper, the problem of exponential synchronization for a class of chaotic neural networks which covers the Hopfield neural networks and cellular neural networks with reaction-diffusion terms and time-varying delays is investigated. A feedback control gain matrix is derived to achieve the state synchronization of two identical neural networks with reaction-diffusion terms, and the synchronization condition can be verified if a certain Hamiltonian matrix with no eigenvalue on the imaginary axis.

Abstract: Dye-free coloration in dyeing and printing for tussah silk were studied in different conditions. The optimal processes of dye-free and printing has been got. The optimal process of dye-free was PHBA1.5%, acid 14%, 60°C for 30 min, then add H₂O₂ for oxidation. And the optimal printing process of dye-free was PHBA2.0%, acid 18%, steam for 20 min after being printed. Colored and printed tussah fabric reactions occurred in the fabric itself, so the mechanical properties of chromogenic fabric unchanged almost, which had excellent color fastness and levelness.

Abstract: This paper introduces an improved sliding mode observer for sensorless control of PMSM. In order to reduce the chattering phenomenon of traditional sliding mode observer, replace the ideal switching function with sigmoid function and use two-stage low frequency filter. At last, the simulation was done to verify the measures.

Abstract: This paper discusses training structure and procedure about inversible system of neural network. Feedback linearization and adaptive neural networks provide a powerful controller architecture. Finally, this paper surveys the status of nonlinear, and adaptive flight control, and summarizes the research being conducted in this area. A description of the controller architecture and associated stability analysis is given.

Abstract: Electric power-assisted steering(EPAS) bench system can be used for fatigue and functional testing of automotive steering .To get a better performance and higher precision of EPAS system, theory analysis and simulation about passive loading system is carried out in this paper. A new strategy combined particle swarm optimization with PID algorithm is put forward to solve the shortcomings of traditional method. Simulations in different methods show the effectiveness of it.

Abstract: With the rapid development of the automotive industry, the demand for gasoline increases sharply. The gasoline cars cause serious environmental pollution. The application of electric vehicles can solve these problems. In this paper, the significance for developing electric cars is stressed first. Then the recent progresses in developing electric car battery, charging technology, drive motor are summarized. Different type of batteries and charging methods are introduced and their feasibilities are analyzed. The future trend of electric vehicles has been discussed as well. With the development of key technologies in electric car manufacture, todays energy and environmental problems will be solved to a large extent.