Advanced Materials Research Vol. 1055

Abstract: This paper describes the importance of increasing control of technology and quality of road bridge construction and puts forwards effective measures to control the proposed road bridge construction technology and quality. Road bridge engineering is a basic livelihood projects while also ensuring economic and social development, but in recent years the reports about the quality of bridge construction repeatedly appeared in press which highlighting the poor construction quality control.

Abstract: This paper is contrary to the seat multi-dimensional problem basing on task space. Using double triangle steward parallel mechanism as the main structure of the seat suspension, according to the sensitive frequency range and the natural frequency of vehicle body, we optimize the design of the suspension system. Research shows that the optimized design of the double triangle Stewart parallel suspension seat suspension system to ensure vertical, pitch, roll three of the more important natural frequency both directions away from the vehicle's natural frequency, but also avoid the human body sensitive frequency range.

Abstract: The main winch of rotary drilling rig is mounted not only on the platform, but also on the lower part of drilling mast. To explore the effect of mount position of the main winch on drilling mast strength, two mathematic models including axial force and moment of drilling mast are established respectively with the main winch mounted on the platform. When the main winch is mounted on the lower part of drilling mast, axial force and moment of drilling mast can be presented by simplifying above two models. Simulated analyses are performed in MATLAB software and the result displays that the drilling mast shows good general mechanical properties when the main winch is mounted on the platform.

Abstract: According to the problem of large friction resistance exists between the sealing ring and the cylinder block when the piston cylinder works, the drag reduction technology of bionic concave surface was applied in the sealing ring. By building a drag reduction motion model of sealing ring with concave surface of triangular arrangement, the effect of drag reduction performance decided by concave diameter and piston velocity was studied with the method of numerical simulation. The results show that: when the piston velocity is fixed, the maximum drag reduction rate can be achieved with the concave diameter is 1.5mm, and the maximum drag reduction rate is 15.72%. Meanwhile when the diameter of the concave is fixed, the drag reduction rate increased gradually with the increase of initial speed, the drag reducing effect is best at the speed of 0.6m/s. In the process of piston movement, lubricating oil in concave shakes, and makes the lubricating oil flow to the inside wall of cylinder, which play the role of lubrication, so as to achieve the effect of reducing friction and increasing the movement speed of piston.

Abstract: The modular multilevel converter (MMC) does not need clamping devices and multiple independent DC voltage source and has a modular structure which is easy to be extended to any level, share a DC side, easy to direct back to back four-quadrant operation and attracts widespread attention. Due to the use of sub-module MMC suspended on the DC side capacitor voltage divider provides synthetic AC output voltage required voltage level and therefore it is essential to the stable operation of the sub-module capacitor voltage balance of the MMC. In this paper, the factors affecting the MMC sub-module capacitor voltage balancing has been carried out a detailed analysis and this paper focuses on the nominal frequency erupted module capacitor voltage control strategies and the average low frequency sub-module capacitor voltage ripple suppression strategies.

Abstract: With the study subject of the gear transmission in an unmanned system, several common methods of fatigue life prediction are analyzed. According to the actual running state, S-N nominal stress method is used to predict the fatigue life of the gears. Based on the S-N data of the gear material and the linear cumulative damage theory, ANSYS is used to estimate the bending fatigue life of the gears, so as to obtain the fatigue life loss coefficient of the gears. It provides a reliable data reference of the design, use and maintenance of the gear transmission in unmanned system.

Abstract: A new method for predicting the grinding force is developed in this paper. The grinding forces model is build by divided it into cutting deformation force and sliding force and combine the undeformed chip thickness which assume the height of grits obey the Rayleigh distribution. In this model, the influence of processing parameters on friction is considered and takes into consideration the kinematic conditions, material properties, wheel microstructure and dynamic effects. In the last, this new grinding model is tested and verified.Keywords Grinding force; Undeformed chip thickness; Ground finish

Abstract: According to Rankkine method, it finds a simple method to calculate the ultimate bearing capacity of reinforced concrete columns subjected to four-faced heating. This method is based on the study results by Dotreppe. And the concrete structure design Specification (GB50010-2002). Sixty-four columns from three different laboratories have been calculated by this method, and safe and correct results are got. An example using the simplified formulation has been presented. It can find that the method is simple and convenient, so it is fit for Chinese engineers.

Abstract: Based on NEWTON and dynamical analysis the half car model is built, in which air spring is a nonlinear system on the basis of force model and the shock absorber has soft and hard states. By the simulation of the model and combination with experiments, the model is proved right and the influencing factor of angle-displacement and acceleration of body can be gained. Then with the application of genetic algorithm in Matlab tools, appropriate control parameters is being set, the above-mentioned model can be optimized, results of optimizations will be compared with three ride comfort evaluation indexes before optimizations. By judging the corresponded extents of curve before and after optimizations, it shows that the parameters after optimizations can improve the ride comfort.

Abstract: The use of solar energy is increased now due to its renewable and pollution-free characteristics. The grid connected dc-ac inverters are largely needed for solar power generation which can be used for power transmission and distribution. The electrical power supplied by the solar arrays depends on temperature, isolation and array voltage. It is therefore necessary to adopt MPPT in order to bring the solar array operating voltage near the peak power point. It will help in drawing maximum possible power from the array. This paper presents various techniques used for achieving this target and compares them with each other to know the benefits and drawbacks with each method.Keywords: MPP, P&O, IC, PV, TF.