Advanced Materials Research Vols. 328-330

Abstract: The high-speed railway based on electromechanical integration develops rapidly in China in recent years. In order to improve research for electrified railway, a model of AC-DC-AC electric locomotive is established using electro- magnetic transient software PSCAD/EMTDC. In this paper, a single-phase tri-level rectifier of unit power factor and its control strategy of direct transient current control method are introduced at first. And then the working principles of the voltage space vector control strategy of inverter and the vector control strategy of cage motors are analyzed. The inverter and the motors must be as a whole because of the realization of motor vector control based on SVPWM inverter. At last, a model is established and the correctness and effectiveness of the model can be verified by the corresponding theory results. The simulation model is useful for the analysis of low frequency resonance in locomotives. The results will be applied in the research of mechanics and electric coupling in high speed electrified railway.

Abstract: The structure design of gun according to the flow velocity and flow energy loss of the fluid in water cutting gun jet channel. Take the gun body plus filter method to solve when the water knife nozzle is small that easy jams. Adopt replaceable type jet tube solve appear jams when cannot promptly eliminate malfunction. Use adjustable grip handle solve the different length require in different surgery. Adopt casing tube wall approach to solving the negative pressure attract residual tissues and cells is not easy cleared.

Abstract: Shanghai YinChaoChang a W722 lathe processing of metal parts, workpiece surface machining quality external circular no obvious problem, and the machine's vibration is small. But in the processing of main parts - rubber managers stamped drum, workpiece surface appear periodically outside round the chatter marks, general examination of hard to find the failure causes of machine tools. We adopt mechanical fault diagnosis technology to find fault location and fault machine of the machine, first nature of transmission chain of analysis and calculation, obtains each train parts, use characteristic frequency JGZY - 1C type mechanical failure diagnosis in the daily use of the lathe spindle 560 turn/points and 735 turn/cent two kinds of rotating speed sensor separately carried on the test, pick up the spindle box, respectively go knife box and slip board box to collect the vibration signal of signal filtered (stationary fault) and demodulation spectral analysis, got a lot of lathe vibration signal spectrum diagram. And the calculated value and vibration signal spectrum diagram compares analysis, find out the fault location and machine determine the fault properties. Replace the corresponding gear and bearing, fault phenomena disappear.

Abstract: A novel fast scanning method is proposed to further stabilize and fasten the construction of extension velocities in level set method. Based on the partial differential equations and scanning schemes, the proposed algorithm only needs our four times to sweep and simple operations to build an extension velocity in O(N) time, where N is the number of grid points. The extended velocities are continuous and preserve the signed distance function without need for re-initialization. Moreover, the fast scanning algorithm has no dependence on the construction of the signed distance function. At last, the presented classical examples show that the proposed approach is accurate, simple and efficient.

Abstract: The virtual manufacturing is an advanced manufacturing technology which came into being in 1990s. Due to fierce market competition, manufacturers are making radical changes in management practices and investing greatly in advanced technologies in order to achieve sustainable competitive advantage. Under this circumstances, the virtual manufacturing technology was formed gradually. Nowadays, the concordant understanding of virtual manufacturing is: set up the virtual model of production system and then simulate the real manufacturing process. According to that, it’s obvious to find that without real manufacturing process, the satisfaction of virtual model production system can still be verified. If some changes about the virtual manufacturing model need to be done for optimizing production system, the right of making corresponding changes is rested in manufacturer’s hands and it’s easier to obtain the optimization by the means of virtual manufacturing than the traditional ones. Virtual manufacturing has made rapid progress in the 21st century. This article introduced the definition and characteristics of virtual manufacturing and its classification and key technologies, its development and application situation, and finally, we pointed out the developing trend of virtual manufacturing and gave some suggestions on that.

Abstract: Traveling load and rotating load can be applied to the tool on the basis of analyzing the relative position between tool and workpiece in assemble model of finite simulation, a finite element model based on trochoid-motion is built. In order to reduce the simulation time, the transition mesh method was used to optimize the finite element model. This paper considers performance parameter of the workpiece, and studied the variation regularities of milling force on the Aeronautical thin-walled by using ABAQUS. At last the experiment shows that the finite element model was verified to be feasible, and the result is reliable.

Abstract: Aircraft tow-tractor is one of the absolutely necessary ground support equipments (GSE) in the airport. The chassis is the framework on which the body and working parts of the tow-tractor, what plays a significant role in a entire vehicle design. The endurance and rigidity of the chassis have a direct influence on the reliability and practicability. In this paper, a simplified model is established for the carriage of aircraft towbarless tractor on the three-dimensional modeling platform--Proe5.0, and then mechanical finite element analysis are proceeding by Ansys12.0. The results show that the chassis model is of a appropriate structure and the design coincides with actual requirements, the Stress Concentration at the joint between carriage and wheel-grip mechanism has been reduced substantially. All trial results have laid a foundation for future design of the entire tractor.

Abstract: In order to explore the influence of slide stroke curves on drawing process and solve the problems of springback and serious thickness thinning during forming, the deep drawing processes of box shaped part based on the conventional mechanical press and servo press were simulated. The springback and thickness variation of box shaped part by different slide stroke curves were obtained. It shows that comparing with the deep drawing with conventional mechanical press, the springback of drawn workpiece decreases by pressure-keeping drawing; the maximum thickness thinning ratio of drawn workpiece is smaller by staged drawing, and the distribution of workpiece thickness is more uniform.

Abstract: The processing performance is closely related with dynamic performance and the dynamic performance is one of the most important performance indicators which is affecting the performance and product quality. The machine is affected most by the dynamic performance of machine bed. The modal analysis method is used to analyze the dynamic performance of the machine. In this paper, the modal analysis of lathe bed is conducted. A 3D solid model of HTC100 NC lathe bed is built with SolidWorks. In order to facilitate the finite element analysis, the model of lathe bed is simplified. The modal analysis of lathe bed is calculated with ANSYS Workbench 12. The first six natural frequencies and corresponding modes are obtained through modal analysis of the lathe bed. According to the low-order natural frequency and modal vibration shapes, the rigidity vulnerable area of lathe bed is realized, which provides the reliable theory to improve lathe bed structure.

Abstract: The Japan Fukushima nuclear crisis upgrades global discussion about the development and utilization of the nuclear power while provides experiences and lessons for the development and utilization of China's nuclear power. From the perspective of national economic security, the essay deals with the development and utilization of nuclear power for the purposes and giving some suggestions on developing a strategy to protect national economic security, building national economic security system.