Applied Mechanics and Materials Vols. 543-547

Abstract: A novel design of flat chip-size microchannel heat sink for high power devices cooling is proposed and optimized. The inlet of cooling media is placed in the highest heat flux region, leading the coolest media into the region with the highest temperature directly, and as a result, the overall cooling efficiency is improved. Simultaneously, the collect channel is set and the inlet position is slightly off-center, which achieves a uniform temperature distribution. With the aid of a computational fluid dynamics (CFD) method, the temperature distribution of microchannel heat sink under steady-state conditions is examined and the microchannel distribution is optimized, forming an optimal design for the chip-size microchannel heat sink.

Abstract: In this study, we developed a new method to fabricate microcoils with narrow and high aspect ratio coil lines using TSV and UV-LIGA technology in a SU-8 mold. The combination of SU-8 and TSV makes it possible to fabricate microstructures with high aspect ratio. TSV technology resolved the difficulties of electroplating with high aspect ratio. We designed and fabricated microcoils consisiting of coil lines with widths of 15μm and aspect ratio of 2.

Abstract: With the rapid development of Internet technology throughout the world, the technology of DSP has progressed tremendously. The paper conducts a research on the routing algorithm based on DSP routing module in medium-voltage power line communication. It attempts to improve link state routing algorithm based on OSPF protocol so as to enable all the circuits of the communicated DSP chips to send and receive data in real-time detection.

Abstract: Typically photovoltaic (PV) maximum power point tracking (MPPT) system concerns in PV output power at specific high solar irradiance. Poor response may be found when load side characteristic is considered particular at low solar irradiance. A novel PV MPPT scheme is present by integrating load power signal into MPPT control signal. The simulation results show that the proposed MPPT system can be operated efficiently at significantly lower solar intensity compared to those of the conventional P&O MPPT system.

Abstract: Cable condition-based maintenance is a high pertinence maintenance mode, with a good time effectiveness and economic comparing with planned maintenance. Three steps are needed in the procedure of practicing condition-based maintenance on coal mine, which are choosing state parameters, on-line monitoring, and state diagnosis. Having an advantage and disadvantage analysis on common on-line monitoring methods, the methods are corresponding to different state parameters. Combining with the actual condition of mine, present that the additional low frequent current method is easy to perform, meanwhile, the method is both fit for MVV, MYJV cable and MYP cable. Separately introduce two kinds of on-line diagnosis methods, one is based on the decision tree, and the other is base on fuzzy grey theory. The former adopt minimum entropy to choose testing feature, furthermore generate sub trees, the latter choose weight coefficient which according to the professors experiences to form cable diagnosis model. State diagnosis is the core in cable state maintenance, so how to establish an intact, scientific diagnosis model is the key.

Abstract: This paper presents three dimensional nonlinear finite element modeling of giant magnetostrictive materials. The nonlinear relationship between magnetostrictive strain and magnetic field is described by experimental curve. Model is implemented using finite element software CMOSOL multiphysics 3.2a. A new method for precise machining non-cylinder pin hole of piston by using embedded giant magnetostrictive smart component is presented. The effects on smart component deformation and the system resonance frequencies are studied. This model is verified against experimental results, with a good agreement.

Abstract: The verification test method on DTS system for power cable conductor-temperature calculation accuracy is described in this paper. The DTS temperature measure accuracy and positional accuracy are tests firstly. During the test a power cable laying in tunnel and applying different load currents ,the conductor-temperature measured value and the DTS system calculated value were compared. Testing process are employs the T-type thermocouple for conductor-temperature measure. DTS system calculates the conductor-temperature according to load current, over-sheath temperature etc. The difference between measured and calculated value were analyzed and compared, that was used for verify the accuracy of the power cable conductor temperature calculated by the DTS system.

Abstract: The impulse voltage test for power equipment such as GIS is not performed in the field for the impulse voltage generator huge and difficult to operate. The oscillating impulse voltage that proposed by IEC60060-3 is a higher generation efficiency impulse waveform and suitable used in field. The oscillating lightning impulse voltage generator for a 110kV GIS field test is studied in this paper. The generator structure is described and the waveform parameter computer formula is derivate. Simulation and test shown the generator can produce impulse voltage that meet IEC60060-3 requirement.

Abstract: Doubly-fed induction generator has become one of most popular generators driven by wind due to its superior behavior in power system. Because of the different physical structures between doubly-fed induction generation units and normal synchronous units, they behave differently in the failure of power system. Based on the analysis of transient behavior of doubly-fed induction generator units, the transient stability of power system integrated with doubly fed induction generator considering different integrating points is discussed. The simulation results verify the validity of the conclusion at the last of this paper.

Abstract: Electromagnetic coilgun and obstacle-striding mechanism are creatively integrated into the foldable obstacle-striding electromagnetic coilgun. According to the theorem of kinetic energy, permanent magnet NdFeB is used as a collisional armature to accelerate the projectile through a central collision. Meanwhile, structures such as shaft in shaft mechanism are designed. Both of the late-model mechanisms make the physical overall structure simple, compacted, and better capable of obstacle striding and operating performance. The testing results and operating performance of this late-model foldable obstacle-striding electromagnetic coilgun appear to be excellent through observing and analysing the results of experiments. It can successfully cross stairs, steps and other usual obstacles. If the stage and the number of turns of induction coil are increased, with safety protecting device, this equipment will be able to put into practice further in particular fields, for instance, military, anti-terrorism, tall building fire fighting and so on.