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Zhu M.,Jiangsu UniversityJiangsu | Wang K.,Jiangsu UniversityJiangsu | Zhang P.,Jiangsu UniversityJiangsu | Li Z.,Jiangsu Chaoli Electrical Co.Jiangsu
Journal of Vibroengineering | Year: 2015

The numerical investigation of automotive cooling fan module aerodynamic noise based on Computational Fluid Dynamics (CFD) / Computational Aero Acoustics (CAA) hybrid method is taken. Considering the influence of fan shroud, an aerodynamic steady simulation is made at first, and then Large Eddy Simulation (LES) with the Smagorinsky model is applied to capture the unsteady pressure data on fan surface. Based on Lowson formula, a prediction of aerodynamic noise is made by Boundary Element Method (BEM). Finally, the prediction results are compared with the experimental results, which show that the acoustic response is with a strong dipole character. Sound pressure level (SPL) at receive points increased with air flow rate. SPL at outlet was higher than inlet. Tonal noise was the major component of the aerodynamic noise. Broadband noise was relatively lower and distributed evenly. Predicted results is consistent with the experimental results, which validates the numerical prediction method. This method can provide a reference to acoustic optimization. © JVE INTERNATIONAL LTD.

Chen X.,Jiangsu UniversityJiangsu | Jiang L.,Petrochina | Wang J.,Yangzhou University
International Journal of u- and e- Service, Science and Technology | Year: 2015

Today distributed server systems have been widely used in many areas because they enhance the computing power while being cost-effective and more efficient. Meanwhile, efficient multi-scheduling schemes are employed to optimize the task assignment process. This paper closely explored the performance of multi-scheduling schemes through computer simulation. The research was started regarding the simulation of a novel scheduling policy (Task Assignment by Guessing Size) associated with other two previous task assignment policies (Random and JSQ). The multi-scheduling schemes involve two types: Random-TAGS scheme and JSQ-TAGS scheme. To facilitate the performance, computer simulation is applied to perform the statistical measurements. The findings were, indeed, very interesting, showing that the multi-scheduling scheme obtains better performance than single scheduling strategy scheme under heavy-tail distributed computing environment. Furthermore, JSQ-TAGS scheme is more efficient and stable in contrast to Random-TAGS scheme. The paper finally concludes by summarizing the findings from the simulation and suggesting a wider study be undertaking, in order to explore the performance of multi-scheduling schemes in more depth. © 2015 SERSC.

Hu Z.,Nanjing University of Aeronautics and Astronautics | Hu Z.,Purdue University | Hu Z.,Soochow University of China | Hu Z.,Jiangsu UniversityJiangsu | And 8 more authors.
Journal of Materials Processing Technology | Year: 2016

Laser sintered graphene nickel (Gr-Ni) nanocomposites have been successfully fabricated, with uniform dispersion of graphene nanoplatelets in the nickel matrix. Microstructures and composition of the nanocomposites were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and Raman spectroscopy. It was demonstrated by EDS maps, XRD patterns and Raman spectrum that graphene nanoplatelets were uniformly integrated in the nickel matrix. TEM images further proved the structure and uniform distribution of graphene in the nanocomposites after laser sintering. HRTEM images revealed the interface between nickel and graphene. High density of dislocation was discovered around the graphene. The strength and elastic modulus of the nanocomposites are significantly improved, as characterized by nanoindentation tests. The hardness tests show that the laser sintered Gr-Ni nanocomposites are around 3-fold higher than that of laser sintered nickel. The strengthening mechanism was also studied theoretically. © 2015 Elsevier B.V.

Ji Y.,Jiangsu UniversityJiangsu | Yu C.,Jiangsu UniversityJiangsu | Weixing H.,Jiangsu UniversityJiangsu
International Journal of Simulation: Systems, Science and Technology | Year: 2016

In biomedical signal processing, the important signal is always within strong noise, and leads to error diagnostics. In this paper, a signal processing method based on dual-tree complex wavelet transform is presented. The heart sound signal is denoised by the method. The signal-to-noise ratio and mean square error are used to evaluate the de-noising effects of the dual-tree complex wavelet transform and discrete wavelet transform. The experimental results show that compared with traditional discrete wavelet transform, the dual-tree complex wavelet transform reduces noise more thoroughly and retains boundary and texture characteristics better. The dual-tree complex wavelet transform can be used as a new de-noising method for biomedical signal processing. © 2016, UK Simulation Society. All rights reserved.

Chen Y.-Z.,Jiangsu UniversityJiangsu
Journal of Mechanics | Year: 2015

This paper provides a general solution for a crack embedded in multiply confocally elliptical layers in antiplane elasticity. In the problem, the elastic medium is composed of an inclusion, many confocally elliptical layers and the infinite matrix with different elastic properties. In addition, the remote loading is applied at infinity. The complex variable method and the conformal mapping technique are used. On the mapping plane, the complex potentials for the inclusion and many layers are assumed in a particular form with two undetermined coefficients. The continuity conditions for the displacement and traction along the interface between two adjacent layers are formulated and studied. By enforcing those conditions along the interface, the exact relation between two sets of two undetermined coefficients in the complex potentials for j-th layer and j + 1-th layer can be evaluated. From the traction free condition along the crack faces, the correct form of the complex potential for the cracked inclusion is obtained. Finally, many numerical results are provided. Copyright © The Society of Theoretical and Applied Mechanics, 2014.

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