Advanced Materials Research Vols. 443-444

Abstract: For the large numbers of material classification coding rules and components in manufacturing enterprises, a computer-aided material classification coding model is proposed, in order to improve the inputting efficiency of part codes. Based on the analysis of the material classification and coding rule for mechanical product, four types of code segments which suited for computer assisted are put forward. The application and database storage models of the coding rule are built up. Moreover, the paper describes the computational workflow of computer-aided coding and its kernel algorithm to acknowledging the related classified segment. The effectiveness and modularity of the prototype system is illustrated by the implementation in an electronics manufacturing corporation.

Abstract: The sensitivity of various features that are characteristics of machine performance may vary significantly under different working conditions. Thus it is critical to devise a systematic feature extraction (FE) approach that provides a useful and automatic guidance on using the most effective features for machine performance recognition without human intervention. This paper proposes a locality preserving projection (LPP)-based FE approach for machine performance degradation recognition. Different from principal component analysis (PCA) that aims to discover the global structure of the Euclidean space, LPP is capable to discover local structure of the data manifold. This may enable LPP to find more meaningful low-dimensional information hidden in the high-dimensional observations compared with PCA. This experimental result on a bearing test-bed shows that LPP-based FE improves the performance of recognizers for identifying performance degradation of bearings.

Abstract: The underwater vehicle has never been able to shake off the mode of pushing forward by the propeller and changing motion with underwater fin rudder. However, this traditional propeller propulsion has many shortcomings, such as a low utilization rate of energy and poor flexibility. In this passage, through the analysis of the movement of sea turtles, a brand-new propulsion project is proposed, which is Flapping-Wing propulsion. In such a limited way to proceed forward, the design can be realized like turtles campaign.

Abstract: - In this paper, the robust control problem of the doubly fed induction generator (DFIG) wind turbines is investigated based on Hamiltonian energy method. A nonlinear design method is proposed for the double-machine system, such that the closed-loop system is stable simultaneously under the action of the controller. Moreover, we study the robust control problem of double-machine system in the presence of disturbances. On the basis of the proposed theorem, the Hamiltonian controller is designed to render the closed-loop system finite-gain stable. In order to illustrate the effectiveness of the proposed method, the simulations are performed which show that the gotten nonlinear controller can enhance the transient stability and improve the robustness property of the closed-loop system.

Abstract: The automatic stuffing lubrication system can appropriately provide a fixed amount of high-voltage grease for each lubrication point according to the conditions under which a vehicle is operated, thus stuffing and lubricating vehicles while they are on the move and automatically monitoring the lubrication conditions during the entire process. The essay focus on not only the analysis of the working condition of chassis centralized stuffing lubrication system, the functions and proper use of controller ,sub-oil device ,lubrication pump , but also the analysis of the installation and testing methods of centralized grease lubrication system.

Abstract: The change of mechanical torque is usually ignored in small disturbance of power systems, which means that influences of the hydro turbine and governor system (HTGS) have been ignored. The disturbance characteristics of the hydro turbine generating units including the HTGS is studied based on torque coefficients method in this paper, and calculating method and expressions of torque coefficients of the HTGS are given. The additional mechanical damping produced by the HTGS can be expressed as D_tΔω, therefore, it can be merged into the damping item in the motion equation of generator, that means that its action is equivalent to modify damping coefficient D. Using a case, the analysis and calculation method are introduced, and several conclusions are given.

Abstract: The collapse surface of surrounding rock induced by the excavation has significant influence on the stability and supporting structures of deep-buried tunnel since located in high in-situ stress field. Based on the assumption of curved velocity discontinuity surface, the internal dissipated power along the surface was calculated in the framework of Power-Law nonlinear failure criterion. In considering the role of supporting forces, an objective function composed of external rate of work and the internal energy rate of dissipation was constructed by using the upper bound theorem of limit analysis, and the analytical expression of collapse surface was obtained with the help of variational calculation. The effect of parameters on the collapse surface was analyzed. It is found that the height and width of the collapse block increased with the rise of nonlinear coefficient m, which illustrate that the nonlinear coefficient m has significant influence on the shape of collapse block. In the limit state, the height and width of the collapse block increase with the growth of supporting pressure.

Abstract: Crack in the port crane which is prevalent in the metal structure of crane is a serious threat to the safety use of crane, therefore, it is very important to study on the production and repair of the cracks. This article takes the actual operating portal crane as an example to study on the crack locations and monitoring methods for metal structure of port crane, with the analysis for the reason of crane load bearing structure’s cracks ,this paper gives the common repair method for metal structure crack for cranes on this basis.

Abstract: Large –scale aluminum ring rolling mill is the core of ring rolling ,it is required for automatic control system to realize high precision and fast response.Based on the configuration of the equipment, characteristics of ring rolling and the process flow of production, the paper not only studied the Control principle of the automatic control system but also designed the control scheme of software and hardware. The core of system is PLC. The system can effectively control hydraulic system, measurement system, feeding servo system by the cooperation of PLC and human machine interface (HMI). It realized fully automatic operation under the ring rolling mill close-loop control. The high precision control and safe operation can be realized by using multi network communication technology and advanced full AC drive system .The rolling quality of rings is high. The design accords with the control logic requirements of rolling process control. The control system is smooth and reliable.