Advanced Materials Research Vols. 655-657

Abstract: New quick-response and high efficiency direct torque control method of Permanent magnet synchronous motor is proposed. The new method is realized by optimizing the switching frequency of the inverter and choosing the most fit voltage space vectors. Modeling and simulating such marine electric propulsion system using Matlab/Simulink is performed. The starting-up and dynamic simulation results prove that this method can be fully used onboard the future all electric ship.

Abstract: Nonlinear vibration damage of pipes conveying fluid is a major problem in today’s production and life. Enormous economic loses and safety hazards were caused by nonlinear vibration. Pipes conveying fluid with various branches are very common in actual engineering. Their mechanical properties and vibration mechanism is quite different from that of pipes conveying fluid without branches. This paper showed the nonlinear vibration mechanism of pipes conveying fluid with vertical branches and nonlinear vibration damage factors. Nonlinear vibration theory was used to check the pipeline and some reference data for the rational selection of working parameters were provided.

Abstract: By using Matlab, the circumferential clearance changing law with any swing angle and rotating angle of four-ball-pin CVJ was obtained, the results show that, under the same size specification and machining accuracy, four-ball-pin CVJ has a roughly similar vibration amplitude with traditional tripod CVJ, when the CVJ rotates one circle at any swing angle, there are four fluctuations of circumferential angle in four-ball-pin CVJ, but there six fluctuations in tripod CVJ, so the former one fluctuate less and has much more slight impact on the vibration and noise during traveling. These results provide a theoretical basis for development and application of this new structural form of four-ball-pin CVJ.

Abstract: A flexplate is a mechanical component that couples the crankshaft to the torque converter of a car with automatic transmission. A higher axial stiffness is one of significant requirements for it in order to ensure its performance. In this paper an optimum design of the flexplate disk is described that maximizes the axial stiffness of the flexplate disk with weight and inertial moment constraints. The strategy for optimizing the layout of the disk is to perform topology optimization first then position optimization. The relation is presented which shows the variation of axial stiffness with respect to changes of the number, shape and position of the holes on the flexplate disk. The research shows that the shape of the hole punched on the disk does not affect the axial stiffness greatly. Thus, the manufacturing cost should be considered first in the optimum design of the flexplate disk

Abstract: Water-lubricated graphite bearing has gradually obtained the widespread application, with its high wear resistance, high temperature resistance and self lubricating, This paper designed the water-lubricated graphite sliding bearing performance testing platform and studied the factors that could affect bearing friction wear rate and the vibration of bearing, such as load, speed and running time. The final results show that the water-lubricated graphite sliding bearing can basically meet the requirements of the blower shaft system.

Abstract: Adopting the test rig of traction characteristics of grease-lubricated sliding bearing, the practical condition of sliding bearing was simulated and the traction coefficient of DGG Grease under different temperature, velocity and load was tested. Besides, the traction characteristics of the grease were also elaborated. The results indicate that the traction coefficient increases when the temperature gradually rises from room temperature while it gradually decreases when the temperature exceeds 85°C. Under the condition of high temperature and high pressure, the extreme pressure additive has obvious effects, the traction coefficient reducing and maintaining constant, so a better lubrication effect is realized.

Abstract: Medical equipment systems are precision system. There are some vibrations and impact in field vehicles from road or field environments. Therefore, shock absorber is significant in protection of medical equipment in moving vehicles. The objective of this paper is to provide a systematic investigation to design or evaluation of a shock absorber for protection of medical equipment system in harsh vibration-impact environment. A novel wireless damping shock absorber is designed and manufactured through coupling friction and spring. The physical mechanism of a prototype shock absorber is systematically investigated by dynamic test. A nonlinear dynamic model for the shock absorber is presented by analyzing the internal frictional dynamic phenomenon with respect to the prototype. Comparisons between experimental data confirm the validity of the model. In the meantime, evaluation of the importance of some key factors by using the mathematical model for designing is discussed. It shows amplitude and frequency of excitation, as well as ratio of damping area are the key factors to ensure the performances of the shock absorber. The change of these factors will change the working characteristics and performances of the shock absorber.

Abstract: In order to the safe using of underwater explosion container and the efficiency, we must accurately determine the strength of the container. In the paper, researching on the design of 1kgTNT equivalent cylindrical explosion vessel it is indicate that strength calculation to explosion vessel using the dynamic coefficient method is accuracy. Experimental results also show that the security of the explosion vessel has reached the design requirements.

Abstract: Data aggregation is the important method to reduce data traffic and lower energy expenditure in wireless sensor networks (WSN). This paper analyzes the characteristics of data sampled by nodes, and gives the method to decide spatial correlation between neighboring nodes and the criteria to classify and decide data in WSN. On the basis of this, this paper proposes a spatial correlation based data aggregation algorithm for WSN, SCBD. SCBD classifies and decides data according to data criteria and spatial correlation among nodes in normal nodes and cluster heads at the same time, and then aggregates different types of data. The results show that SCBD outperforms RAA in terms of energy consumption, rate of data detection and quality of data aggregation.

Abstract: Considering the requirements of energy saving and data aggregation, and the characteristics of spatial-correlation and temporal-correlation in wireless sensor networks (WSN), this paper proposes a spatial-temporal correlation based novel clustering algorithm, STCBCA. In cluster formation phase, STCBCA clusters nodes in the network according to the spatial correlation between nodes and cluster heads. In data gathering phase, STCBCA clusters data sampled by nodes via the criterion of data cluster, and then sends them to the cluster heads. Our results show that STCBCA can reduce data traffic, prolong network lifetime and improve quality of data aggregation against the clustering algorithm DCAM.