Advanced Materials Research Vols. 468-471

Abstract: This paper is concerned with a mathematical model for simulating hydrodynamics of 2D circular dam-break flows with the WENO scheme and the Finite Volume Method. The time discretization uses the Runge-Kutta TVD scheme. By using the proposed model, we calculated the flow property of circular dam-break, and obtained the flow velocity field distributions. The calculated results show that the WENO scheme has higher accuracy and better stability, and has the ability to automatically capture shock waves, and may suppress the oscillations of numerical solution. This model can effectively simulate the hydrodynamics of 2D river flow with irregular boundaries.

Abstract: A Doppler diversity receiver for OFDM is proposed by Kim B C[1], which requires channel estimation at the receiver, so its structure is complicated, what’s more, the receiver needs a large amount of calculation. Different from it, we use the differential phase modulation technology in the OFDM Doppler receiver, so the receiver can recover the original data without channel estimation, and the implement is simple, the computational complexity is low. However, experiment results show that the BER of the new receiver is higher than the conventional, and it can not get performance gains by diversity either.

Abstract: Parallel arranged tri-screw extruder (PATSE) is a new machine of polymer processing and first manufactured in recent years in China. Compared with the traditional twin-screw extruder, PATSE adds a screw, and added an intermeshing region. It is well known that material going though intermeshing region will acquire higher shear rate and stretching rate, which is beneficial to mixing processing. In order to know the mixing performance in cross-section for PATSE, polymer melt flow field simulation and mixing simulation were conducted on PATSE with 2D model and a Carreau flow model to evaluate velocity profiles, particle trajectories, max shear rate, max stretching rate, dispersive mixing, distributive mixing, segregation scale, length of stretch, mixing efficiency with the commercial CFD package Polyflow and compared with those of twin screw extruder (TSE). The results show that PATSE has better mixing performance than TSE.

Abstract: By using the quarterly data of CPI and GDP in China from 1992 to 2011, this paper builds a smooth transition regression (STR) model to study the nonlinear relation between inflation and economic growth. The results show that there exist two-way Granger causality relations between inflation and economic growth, and inflation has significant nonlinear impacts to economic growth.

Abstract: With the development of modern agriculture, agricultural vehicles have broad prospects for development, for existing problems of the agricultural vehicles spur gear original forging die , designed new precision forging new technology of gear and new type precision forging die to use for production , in order to enhance radial intensity of concave model and reduce the cost of updating die, using fluctuating concave model level bisection ，three-player pre-stressed composite concave model structure ，lock-oriented , top concave model and model core are floating . Forgings parts formed in a closed ring mold cavity ，forging parts without fly side , significantly reduce turning remaining of semi-finished product,the material utilization, production efficiency and quality of forgings significantly improved , gained good economy benefit.

Abstract: This paper introduces the mechanism design theory to establish Stacklberg Game Model in which with perfect information, logistical enterprises are leading decision makers, analyzing the game behavior of inventory financing with the method of backward induction. The results indicate that with perfect information, two-sided market of banks and logistical enterprises has more advantages than one-sided market of banks, and logistical enterprises are willing to improve their risk ratio to gain interest reduction from banks, which can lead to demand for financing.

Abstract: Multiple independent motor driving systems have been applied in various fields nowadays. The speed synchronization of multi motors became a challenge. A new normalized coupling method has been proposed. The simulation result shows the new method could apply on more than two motors. Both same speed and different speed synchronization can be achieved.

Abstract: Numerical simulation of the three-dimensional steady and unsteady turbulent flow in the whole flow field of a multi-blade centrifugal fan is performed. Unstructured grids is used to discrete the computational domain. Pressure boundary conditions are specified to the inlet and the outlet. The SIMPLE algorithm in conjunction with the RNG k-ε turbulent model is used to solve the three-dimensional Navier-Stokes equations. The moving reference frame is adopted to transfer data between the interfaces of the rotating field and the stationary field. Based on the calculation of the inner-flow in the fan, the pressure pulsation of some important monitoring points and the aerodynamic noise distribution, banding together experiment data were farther analyzed The simulation results are of important significance to the optimal design and noise control of the fan.

Abstract: The 3-D steady turbulent flow in a centrifugal pump under different conditions was simulated by ANSYS CFX software. The intensity, location and the morphology of the inlet recirculation vortex were analyzed using standard k-ε turbulent model through steady simulation. Based on the results, the turbulent flow in the impeller inlet was simulated by Large Eddy Simulation. The dynamic characters and the whole changing process of the recirculation vortex during the rotation of the impeller were analyzed. The results indicate that the critical flow rate of the recirculation onset is 0.7Qd. As the flow rate decreases, the size and the intensity of the recirculation vortex increase and the vortex partially block the flow passage. The vortex first appears in the passage which passes by the outlet section of the volute. During one rotating, the vortex undergoes a whole process of onset, developing, decreasing and disappearing. As the relative speed and the pressure gradient change under different conditions, the vortices present different morphologies.

Abstract: This paper studies the structure and principle of tractor automatic mechanical transmission shift actuator with the type (electronically controlled hydraulic). Tractor AMT shift actuator mechanics model and mathematical model are set up. Dynamic analysis of shift process is finished. The method of solving contradiction between shift time and shift impact in shift process is presented. Through analysis of shift process, optimal hydraulic control law could be found out by applying optimal control theory. The most short time shift with low impact even no impact is realized.