Hui H.,Shenyang Blower Works
Advanced Materials Research | Year: 2012
A multi-objective scheduling method based on the controlled Petri net and GA is proposed to the flexible job shop scheduling problem (FJSP). Function objectives of the proposed method are to minimize the completion time and the total expense and workload of machines. Firstly, a Parikh vector based approach for Petri net controller is introduced, and based on this method, the Petri net model is constructed for FSP with machine breaking down. Then, the genetic algorithm (GA) is applied based on the controlled Petri net model and Pareto. Finally, simulation results based on an example show that the method is efficient. © (2012) Trans Tech Publications, Switzerland.
Li C.,Northeastern University China |
Dai J.,Northeastern University China |
Dai J.,Shenyang Blower Works |
Wen B.,Northeastern University China
Lixue Xuebao/Chinese Journal of Theoretical and Applied Mechanics | Year: 2011
Continuous model of rotor-bearing system with double disks supported by cylindrical bearings is analyzed in this paper. Shooting method is used in the stability analysis of the continuous system. The rotor-bearing system with double disks is analyzed by considering the disk eccentric magnitude, eccentric initial phase, bearing clearance, dynamic viscosity of the oil and bearing aspect ratio. Some useful conclusions are found: instability is mainly caused by the period-doubling or quasi-period bifurcation; instability speed can be increased by decreasing the disk eccentric magnitude or increasing the initial eccentric phase difference of the disk; increasing bearing aspect ratio and decreasing bearing clearance properly can inhibit the instability occurring early; the higher dynamic viscosity of the oil is not the better, otherwise oil with lower dynamic viscosity can increase the instability speed properly. Research method and conclusions in this paper can provide theoretical reference for the stability design and vibration control of the more complex rotor-bearing system.
Lu F.A.,Xian Jiaotong University |
Qi D.T.,Xian Jiaotong University |
Wang X.J.,Shenyang Blower Works |
Zhou Z.,Xian Jiaotong University |
Zhou H.H.,Xian Jiaotong University
Journal of Sound and Vibration | Year: 2012
A numerical optimization is presented to reduce the vibration and noise of a centrifugal fan volute. Minimal vibration was considered as the aim of the optimization, and the calculation of sound field induced by the vibration of the volute was only based on the final results of the optimization. After the three-dimensional unsteady flow simulation of a centrifugal fan, the parametric finite element model of the volute was created using the pressure fluctuations at blade passing frequency on the volute as external excitation forces. To validate the finite element model of the volute, natural frequencies and amplitudes of the normal velocities of the volute at blade passing frequency were measured. A good agreement was found between the numerical and the experimental results. Then, random method and first-order optimization method were applied in the optimization process. The numerical optimization of the volute was carried out using the local thickness of the volute as design variables and the quadratic sum of the nodal velocities as an objective function. Numerical optimization results show that the volute vibration is reduced by the optimization method. Finally, vibroacoustics of the volute before and after the optimization were calculated by direct boundary element method. The results show that the radiated power of the vibroacoustics of the volute is reduced significantly as well as the vibration of the volute after the optimization.This numerical optimization process provides a useful reference for vibroacoustic reduction of centrifugal compressors and centrifugal fans whose fluids should be kept strictly in a system without leakage. © 2012 Elsevier Ltd. All rights reserved.
Li X.N.,Dalian University of Technology |
Ding J.X.,Dalian University of Technology |
Xu L.Y.,Dalian University of Technology |
Bao C.M.,Shenyang Blower Works |
And 2 more authors.
Surface and Coatings Technology | Year: 2014
It was previously known that C-doping in Cu effectively enhances the film thermal stability and maintains a low electrical resistivity even upon high-temperature annealing, via a diffusion inhibiting the mechanism of C-stabilized oxide interlayer between Cu and Si. In the present work, the stability and resistivity are investigated in two Cu films doped with more C, respectively 2.9. at.% and 4.2. at.% as measured by EPMA. As expected, the thermal stability is even further enhanced, without significantly affecting the resistivity. After a systematic microstructural investigation by TEM, it is revealed that the relevant mechanism lies both in the enhanced stability via C dissolution in the silica native oxide layer at the Cu/Si interface and in the C-passivated Si surface zone beneath the layer. In the 4.2% C film, the Cu/Si interaction is mainly inhibited by self-forming SiC nano-particles and the resistivity remains below 3. μΩ·cm even upon annealing at 500. °C for 40. h. The C-doping can then be a simple process route towards manufacturing stable Cu interconnects. © 2014 Elsevier B.V.
Zhao Y.Q.,Northeastern University China |
Mao J.H.,Shenyang Blower Works
Advanced Materials Research | Year: 2014
Drill steel is a special steel specifically tailored for drilling rods. To understand the microstructure properties and dimensional accuracy of the drill steel, a rigid plastic finite element method was used to analysis Mannesmann piercing in steel drilling production. The three-dimensional thermal-force coupling FEM models were computer generated with different feed angle. The metal deformation during the piercing process was analyzed in detail. The influence of feed angle on deformation, force, velocity and strain was obtained through simulations. © (2014) Trans Tech Publications, Switzerland.