Applied Mechanics and Materials Vols. 427-429

Abstract: The power transmission steel structures are used in the outdoor and the durability will be decreased due to the various corrosions, so the structures usually coated the anti-corrosion layers such as hot-dip coating, zinc-rich coating or thermal spray zinc coating. The anti-corrosion layers on three power transmission steel structures in Henan province, China were investigated by the corrosion morphology and the residual coating thickness. The results indicated that the corrosion degree of the bolts is higher than that of the steels, and there are local corrosions occurred on the surface of the steels due to the plating leakage or clash.

Abstract: Through the prediction based on reliability counting method, identified weak links of automatic control system, achieved the reliability modeling of marine power station and structured reliability block diagrams and the reliability mathematical models, the reliability and mean time between failures (MTBF) of marine power station are obtained under different work conditions. The marine power station reliability modeling acquired from different work conditions accords with the actual operating mode, and all these work can supply more scientific theoretical support for study on reliability of marine power station.

Abstract: The problem of the critical number of pedestrians is significant in the study of lateral vibrations of footbridges since it can cause serviceability for the footbridges. By considering the pedestrians mass on the footbridge increases slowly, the modified Nakamuras model can be regarded as a fast-slow system which can be used to calculate the critical number of pedestrians. The influence of the time delay of interaction between pedestrians and the footbridge on the critical number of pedestrians is analyzed. Comparison with other results indicates the correctness of our formula predicting the critical number of pedestrians. Furthermore, our research suggests that the existence of the time delay can make the critical number of pedestrians less, which means that the time delay helps to improve the safety of the footbridge.

Abstract: Node modeling of wind farm in power flow calculation is an issue which must be solved. This paper described mathematical model of asynchronous generator which be used widely, elaborated mathematical model and calculation process of several wind farm node models in power flow calculation, discussed calculation speed and accuracy of every model and pointed out that under the premise of high level calculation speed, how to add wake effect to power flow calculation process will be a significant direction for wind farm modeling studies.

Abstract: Based on elastic criterion and regular connection of cable, a new measuring method of tension in cable is introduced in this paper, together with a confirmatory test for this method. The result indicates that this method has many advantages, such as simple principle, high accuracy, good repeatability, remarkable stability, simple operation and wide application.

Abstract: In order to improve the quality of low voltage UV cross-linking product and provide a theoretical basis to the improvement of cross-linking device, the temperature field of cross-section of cable was studied based on the theories of semi-transparent medium radiation and numerical heat transfer in this article. Two cases with different convective heat transfer coefficient of cable surface were researched, and then the temperature distribution in the cable under different boundary conditions of heat convection was analyzed. At last, the temperature field characters of insulating layer and conductor cores in the cable were achieved and a reasonable value range of convective heat transfer coefficient of cable surface was given in this article.

Abstract: The blade is a complex mechanical structure model which has two processing methods. One is making mold blade using the electrochemical methods and forming the blade molding using precision casting methods. But the cycle of this processing method is long and the process is complex and difficult to control. The second method is cutting the blade directly. The cutting force and the friction between tools and blanks can affect the machining accuracy of the machining. We should timely adjust the cutting parameters and cooling model to improve processing accuracy.

Abstract: This paper analyzes the three major problems exist in the long-term use of hydraulic coupler, a temperature rise effect is the hidden trouble of the normal operation of equipment; two is the site difficult to accurately control the charging liquid, starting power balance and shutdown can not control the scraper conveyer; three is the property of medium effects factors of hydraulic coupling torque; introduces the working principle of asynchronous magnetic coupling and unique five technical characteristics. The asynchronous magnetic coupling and hydraulic coupler has obvious technical advantages compared, can solve the long-standing hydraulic coupler in the production practice expect to solve urgently and has failed to solve the problem. Conclusion is the soft starter for asynchronous magnetic coupling for scraper conveyor is completely feasible.

Abstract: It is an important practical design problem for control system design of quadrotor helicopters with accurately actuator modeling, which is not mentioned in many previous works. In order to improve the performance of attitude stabilization control system, a new strategy is proposed in this paper. This control strategy is based on the accurately nonlinear modeling of the brushless motors using the Hammerstein series models. Furthermore the identification method to obtain such models from observed input-output data is presented. After models of four brushless motor are obtained, a backstepping attitude controller is designed to stabilize the quadrotor helicopter. Flight experiments show that the proposed control strategy can achieve higher performance than past ones.

Abstract: Solar heating has a broad application prospects in northern China. A new corrugated solar air collector within the heat plate holes was designed in this paper, and compared to air collector with a flat-plate collector plate in the same conditions, the current state, temperature distribution of the collector and its efficiency was studied, to identified its thermal performance. Experimental verification showed the experimental results accorded with numerical simulation.