Applied Mechanics and Materials Vol. 607

Abstract: This article analysed the impact of speed regulation and power-frequency control on power system low-frequency oscillations from the perspective of its production theory. From the experimental results, it can be seen that the power-frequency control will make the low-frequency oscillations worse and longer, thus need to be modified in further research.

Abstract: We investigated two processes to fabricate unsaturated polyesters, UP, to serve as a stamp to emboss a microfluidic chip to apply to a peristaltic micropump. The mechanical properties of UP are great to apply to vibration type micro-actuators. However, it’s rarely discussed academically. As a result, we proposed two processes developed and compared macro-and micro-scopically. It was first observed that process I of traditional UP curing process and process II of modified process can both replicate the geometries of microfludic chips well macroscopically. In addition, the former one has macroscopic defaults like cracks, bend, and separation between vessel and UP molds, while the latter one doesn’t. Optical microscope and confocal microscope are also applied to verify the replication effects microscopically. Again, both processes illustrate good replication results with variation of both lengths and areas all less than 10%, while process II has better geometries and lower deviation on different sites. The process I was proven that the averages of depth and widest width change rates for replication are-1.06% (between-4.15% and 2.89%) and-2.77% (between-6.93% and 0.67%), respectively. And, the replication results of process II shows also reasonable change and even smaller deviations that the averages of depth and widest width change rates are-4.77% (between-6.33% and-3.84%) and 1.53% (between 1.15% and 2.15%), respectively.

Abstract: Based on the theory of hydraulic transients and method of characteristics (MOC), the numerical model of hydraulic transients in water way system was established using the data of a practical hydropower station, and the probable transients were simulated. The influence of successive load rejection conditions on water hammer pressure of spiral case was analyzed. Compared with simultaneous load rejection, successive load rejection can make maximum pressure in spiral case and maximum rotating speed of runner more serious if the bifurcated pipe converging under surge tank in diversion-type hydropower station.

Abstract: This paper analyzed the influence of various turbine parameters on the low-frequency oscillation using Simulink, including the oil motive slide valve time constant, the volume time constant, power grid damping factor, power grid power factor, self-balancing rotor coefficient etc. Meanwhile, comparing the influence of the pure speed regulator and power-frequency regulation on low-frequency oscillations, proven that power-frequency regulation will exacerbate the low frequency oscillation.

Abstract: This research work aims to identify the characteristic of flow in valveless impedance pump which uses acoustic impedance mismatch to drive flow. The experimental setup mainly focuses on the elastic section connected between two ends of rigid tube. Fluid flow rate resulting from the pumping mechanism were measured at different supply voltage. Meanwhile, the volume flow rate (ml / min) in the elastic tube section were also determined based upon different pinch location and width using water as a working fluid. In order to achieve these parameters quantification, the experimental test rig was designed and the set of equipments were successfully assembled. Then, the measured parameters resulting from the experiment of the impedance pump are presented in significant findings of four curves plots. It is found that the maximum flow rate occurred at voltage setting equal to 4 V. Significantly, results obtained could beneficial future design as a mimics model for novel Ventricular Assist Device use in cardiac patient as well as further explanation about the factor that influence the characteristic of valveless impedance pump.

Abstract: Numerical simulation is used to explore the turbulence noise in pipes generated by high-speed fluid. The characteristics of turbulent noise and its influencing factors are analyzed for different pipe structures and flow rates. The results showed that there is a parabolic relationship between the Overall Sound Pressure Level (OASPL) and the flow rate as the flow rate increases in the pipe. The OASPL of a variable diameter pipe is 20dB higher than that of the straight pipe with a built-in cylinder under the same flow rate. The structure of flow around a cylinder can effectively weaken turbulence noise and reduce high-frequency noise.

Abstract: The job-shop scheduling problem with alternative machines is very complicated and hard to simplify during product management system for discrete manufacturing enterprise. According to the integrated constraint condition of the processing technology and equipment resources, an optimization model for the dispatch plan of processing technology for the gear shaft assembly is analyzed and established in this paper. Furthermore, the optimization results for the process sequence planning of the gear shaft assembly are obtained by iterative algorithm and improved genetic algorithms approach. The calculating program of optimization layout is developed by Matlab. The optimization results show that the production cycle time and operating cost is reduced remarkably and the efficiency is also improved. Through analysis and verification, it is optimal and feasible for discrete manufacturing enterprise in engineering applications.

Abstract: The structure and the load-carrying capability of the front board of injection molding machine are more complex. The error of the approximation algorithm employed in engineering is larger so that the board may become invalid in the process of using, The finite element analysis can obtain the stress distribution in the parts so as to improve the accuracy of calculation and the quality of design; through The topology optimization analysis will take the initiative to find the optimal plan, which provides the theoretical basis for the improvement of the load-carrying capability and the structure design of board. This paper have conducted a parametric design, finite element analysis and the topology optimization design for a motional board of the injection molding machine using “Advanced simulation” of NX8.0, and get a quantitative conclusion of that the motional board volume is reduced and its stiffness is significantly enhanced.

Abstract: The author studied the 4-axis Vertical MC (VMC)，designed and created its general layout feature mode in one CAD platform (the author used Solidworks) with the engineer’s natural thought manner: topdown. The 4-axis VMC’s NC machining simulation is also carried out in one NC mfg verification tool (the author selected Vericut), and the conformability and compatibility are confirmed. The following conclusions can be summarized: the modern NC machine tool designer and user can promote their production quality, efficiency, cost reduction goals with the help of the integration between the CAD and NC mfg verification technology.

Abstract: In this paper the computer aided design and manufacture of a rot with winglet for performance enhancement of a vertical axis wind turbine is presented. Both computer numerical control milling and rapid prototyping have been used in the manufacture of the rotor. The rotor was then tested for performance using the large wind tunnel of the Aerodynamics laboratory of University of New South Wales. The results show substantial improvement of the rotor with the winglets installed.