Papers by Author: Xiao Jun Liu

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Authors: Yi Min Wang, Xiao Jun Liu
Abstract: Vibration is the biggest problem for precise on-line surface measurement. In order to investigate the possibility for phase-shifting interference technique to be applied to precise on-line surface measurement, a synchronic phase-shifting technique is proposed. Its anti-vibration characteristics are analyzed and a vibration table to simulate different vibration conditions is set up, on which many experiments for surface measurement under different vibration conditions are conducted. The analysis and experimental testing verify the excellent anti-vibration characteristics of the interferometer for on-line precise surface measurement.
Authors: Xiao Hui Chen, Xiao Jun Liu
Abstract: Micro-structural defects influence the performance of MEMS devices. For effective quality monitoring and assurance in mass-production of MEMS devices, it is necessary to conduct automatic defect inspection. In this paper, an approach based on image processing for automatic microstructure defect inspection is presented. In the approach, an Influence Region Template is built based on a reference microstructure image while it preserves the framework and restrains the tiny distortion of the reference, then the test microstructure image is compared with the Influencing Region Template for quality evaluation. By the approach, typical defects such as blocks in trenches or channels, transfixions between trenches or channels and missing of some part and so on, are detected and classified automatically, while some distortions which do not affect the function of the microstructures are ignored. Testing results show that the approach can conduct a high quality assurance while it can endure a given distortion tolerance of microstructures.
Authors: Geng Pei Zhang, Xiao Jun Liu, Wen Long Lu, Xiang Qian Jiang
Abstract: Running-in process is an important stage of whole wear process. The irrelevance of surface roughness before and after running-in puzzled the running-in research. However, this conclusion was based on surface roughness derived from the 2D surface profile which does not contain 3D information, and was therefore not complete. In this paper, running-in experiments were conducted to investigate the issue. The results showed that there is no equilibrium surface topography similar with equilibrium roughness at the end of running-in process.
Authors: Kai Hu, Xiang Qian Jiang, Xiao Jun Liu
Abstract: A new signal-denoising approach based on DT-CWT (Dual-Tree Complex Wavelet Transform) is presented in this paper to extract feature information from microstructure profile. It takes advantage of shift invariance of DT-CWT, non-Gaussian probability distribution for the wavelet coefficients and the statistical dependencies between a coefficient and its parent. This approach substantially improved the performance of classical wavelet denoising algorithms, both in terms of SNR and in terms of visual artifacts. A simulated MEMS microstructure signal is analyzed.
Authors: Geng Pei Zhang, Xiao Jun Liu, Wen Long Lu
Abstract: Running-in is an important and inevitable wear process for machine system, and it plays an indispensable role in extending service life and improving operating performance. Surface topography appears as a significant feature of friction pairs. Therefore, study on modification of surface topography in running-in is crucial to control surface quality and then achieve improvement of machine system. In this paper, to understand the evolution of surface topography in running-in process, steel dry sliding running-in experiments were conducted, and surface topographies in running-in were evaluated with the areal surface evaluation parameters. The results reveal that surface topography evaluation could provide valuable information about wear status of steel running-in process of dry sliding friction, amplitude parameters, area and volume parameters, and hybrid parameters play different and important roles in characterization of surface topography modification in running-in.
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