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Articles 1 - 13 of 13
Full-Text Articles in Physical Sciences and Mathematics
Frequency Selection In Absolute Phase Maps Recovery With Two Frequency Projection Fringes, Yi Ding, Jiangtao Xi, Yanguang Yu, Wengqing Cheng, Shu Wang, Joe F. Chicharo
Frequency Selection In Absolute Phase Maps Recovery With Two Frequency Projection Fringes, Yi Ding, Jiangtao Xi, Yanguang Yu, Wengqing Cheng, Shu Wang, Joe F. Chicharo
Dr Yanguang Yu
In a recent published work we proposed a technique to recover the absolute phase maps of two fringe patterns with different spatial frequencies. It is demonstrated that a number of selected frequency pairs can be used for the proposed approach, but the published work did not provide a guideline for frequency selection. In addition, the performance of the proposed technique in terms of its anti-noise capability is not addressed. In this paper, the rules for selecting the two frequencies are presented based on theoretical analysis of the proposed technique. Also, when the two frequencies are given, the anti-noise capability of …
Estimating The Parameters Of Semiconductor Lasers Based On Weak Optical Feedback Self-Mixing Interferometry, Jiangtao Xi, Yanguang Yu, Joe F. Chicharo, T. Bosch
Estimating The Parameters Of Semiconductor Lasers Based On Weak Optical Feedback Self-Mixing Interferometry, Jiangtao Xi, Yanguang Yu, Joe F. Chicharo, T. Bosch
Dr Yanguang Yu
The paper presents a practical approach for measuring the linewidth enhancement factor /spl alpha/ of semiconductor lasers and the optical feedback level factor C in a semiconductor laser with an external cavity. The proposed approach is based on the analysis of the signals observed in an optical feedback self-mixing interferometric system. The parameters /spl alpha/ and C are estimated using a gradient-based optimization algorithm that achieves best data-to-theoretical model match. The effectiveness and accuracy of the method has been confirmed and tested by computer simulations and experiments, which show that the proposed approach is able to estimate /spl alpha/ and …
An Energy-Aware Multilevel Clustering Algorithm For Wireless Sensor Networks, Xinfang Yan, Jiangtao Xi, Joe F. Chicharo, Yanguang Yu
An Energy-Aware Multilevel Clustering Algorithm For Wireless Sensor Networks, Xinfang Yan, Jiangtao Xi, Joe F. Chicharo, Yanguang Yu
Dr Yanguang Yu
Clustering sensors nodes as the basic of routing is an efficient mechanism for prolonging the lifetime of wireless sensor networks. In this paper, the high-efficient multilevel clustering is abstracted as a root tree which has the performances of the minimal relay set and the maximal weight according to graph theory. A mathematical model for the clustering virtual backbone is built. Based on the model, an algorithm called energy-aware multilevel clustering (EAMC) is proposed. The EAMC can reduce the number of relays used for data transmission by minimizing the amount of the nodes in the root tree (that is cluster-head). Furthermore, …
A New Phase Unwrapping Algorithm Based On Three Wavelength Phase Shift Profilometry Method, Limei Song, Xiaoxiao Dong, Jiangtao Xi, Yanguang Yu, Chaokui Yang
A New Phase Unwrapping Algorithm Based On Three Wavelength Phase Shift Profilometry Method, Limei Song, Xiaoxiao Dong, Jiangtao Xi, Yanguang Yu, Chaokui Yang
Dr Yanguang Yu
Phase Shift Profilometry (PSP) method is widely used in 3D shape measurement. The advantage of the PSP method is that it is less sensitive to the surface reflectivity variations and the object can be measured point by point. But if only a single wavelength λ1 is used, the step height cannot be larger than λ1/4. In order to measure step height object, Gray Code (GC) and Multi-Wavelength Phase Shift Profilometry (MWPSP) method are used. But the GC method cannot solve the problem of the objects with a variety of colors under different illumination. The shortcoming of MWPSP …
An Estimation Method For Feedback Level Factor C Of A Self-Mixing Interferometry System, Yuanlong Fan, Yanguang Yu, Jiangtao Xi, Joe F. Chicharo
An Estimation Method For Feedback Level Factor C Of A Self-Mixing Interferometry System, Yuanlong Fan, Yanguang Yu, Jiangtao Xi, Joe F. Chicharo
Dr Yanguang Yu
This paper presents a fast estimation method for feedback level factor C of a self-mixing interferometry (SMI) system. The reconstruction of a displacement waveform using a SMI signal needs to know a C value. However, it is difficult to maintain a constant C value during the reconstruction process. We study the features of the reconstructed displacement waveforms incorporating different pre-set C values and classify waveforms into two types. Bisection method is introduced in our method for fast estimating C value. The effectiveness of our proposed method has been verified by both simulation and experimental data.
A Data-Fitting Approach For Displacements And Vibration Measurement Using Self-Mixing Interferometers, Yi Zhang, Jiangtao Xi, Joe Chicharo, Yanguang Yu
A Data-Fitting Approach For Displacements And Vibration Measurement Using Self-Mixing Interferometers, Yi Zhang, Jiangtao Xi, Joe Chicharo, Yanguang Yu
Dr Yanguang Yu
This paper presents a signal processing approach for vibration measurement using self-mixing interferometer (SMI). Compared to existing approaches, the proposed approach is able to achieve an accuracy of λ/40 which significantly exceeds the accuracy limit associated with conventional simple SMI systems λ/4.
A Calibration Approach For Decoupling Colour Cross-Talk Using Nonlinear Blind Signal Separation Network, Y. Hu, Jiangtao Xi, Enbang Li, Joe F. Chicharo, Zongkai Yang, Yuanguang Yu
A Calibration Approach For Decoupling Colour Cross-Talk Using Nonlinear Blind Signal Separation Network, Y. Hu, Jiangtao Xi, Enbang Li, Joe F. Chicharo, Zongkai Yang, Yuanguang Yu
Dr Yanguang Yu
We present a calibration approach to invert the nonlinear mixing process of colour cross-talk in multi-channel profilometry systems. Parameters of the inverse network are determined by a nonlinear blind signal separation algorithm. Experimental and simulation results demonstrate that proposed approach can effectively reduce colour leakages and improve the measurement accuracy.
3d Face Recognition Based On A Modified Icp Method, Kankan Zhao, Jiangtao Xi, Yanguang Yu, Joe F. Chicharo
3d Face Recognition Based On A Modified Icp Method, Kankan Zhao, Jiangtao Xi, Yanguang Yu, Joe F. Chicharo
Dr Yanguang Yu
3D face recognition technique has gained much more attention recently, and it is widely used in security system, identification system, and access control system, etc. The core technique in 3D face recognition is to find out the corresponding points in different 3D face images. The classic partial Iterative Closest Point (ICP) method is iteratively align the two point sets based on repetitively calculate the closest points as the corresponding points in each iteration. After several iterations, the corresponding points can be obtained accurately. However, if two 3D face images with different scale are from the same person, the classic partial …
Fpga-Based Signal Processing In An Optical Feedback Self-Mixing Interferometry System, Zongzhen Li, Yanguang Yu, Jiangtao Xi, Huiying Ye
Fpga-Based Signal Processing In An Optical Feedback Self-Mixing Interferometry System, Zongzhen Li, Yanguang Yu, Jiangtao Xi, Huiying Ye
Dr Yanguang Yu
Optical feedback Self-mixing Interferometry (OFSMI) can achieve a high-resolution displacement sensing and measurement by using advanced digital signal processing. However, most existing signal processing algorithms used for OFSMI signals are implemented on a PC by Matlab or other programming languages. In this case, the whole structure of OFSMI sensing system is incompact and the measurement is in low speed. The design trends in sensing systems are towarding to small size, high integration and fast real time processing. These trends require us to improve the existing OFSMI design. It is a good solution to apply Field-programmable gate arrays (FPGAs) technique onto …
Partially Overlapped Range Images Registration Based On Fringe Pattern Profilometry, Xiaochen He, Jiangtao Xi, Yanguang Yu
Partially Overlapped Range Images Registration Based On Fringe Pattern Profilometry, Xiaochen He, Jiangtao Xi, Yanguang Yu
Dr Yanguang Yu
Registration of two three-dimensional (3-D) point sets is a fundamental problem of 3-D shape measurement and modeling pipeline. This paper investigates the automatic pair-wise method to register partially overlapped range images generated by self-developed fringe pattern profilometry (FPP) system. The method is based on the classic iterative closest point (ICP) algorithm but combined with several extensions to adapt to the experimental data. Firstly, the distance function for correspondence finding is modified to be the weighted linear combination of positions and Euclidean invariant features for improving the probability of convergence. In addition, outliers can be discarded through robust statistics and adaptive …
Fast Quality-Guided Phase Unwrapping Algorithm For 3d Profilometry Based On Object Image Edge Detection, Ke Chen, Jiangtao Xi, Yanguang Yu
Fast Quality-Guided Phase Unwrapping Algorithm For 3d Profilometry Based On Object Image Edge Detection, Ke Chen, Jiangtao Xi, Yanguang Yu
Dr Yanguang Yu
A main challenge associated with 3-dimentional fringe pattern profilometry (3D-FPP) systems is the unwrapping of phase maps resulted from complex object surface shapes with both robustness and speed guaranteed. In this paper we propose a new quality-guided phase unwrapping algorithm. In contrast to the conventional quality-guided methods, we classify pixels on wrapped phase map into two types by detecting edge pixels on object image: high quality (HQ) pixels corresponding to smooth phase changes and low quality (LQ) ones to rough phase changes. In order to improve the computational efficiency, these two types of pixels are unwrapped by means of different …
Overview On The Profile Measurement Of Turbine Blade And Its Developm, Huang Junhui, Wang Zhao, Gao Jianmin, Yanguang Yu
Overview On The Profile Measurement Of Turbine Blade And Its Developm, Huang Junhui, Wang Zhao, Gao Jianmin, Yanguang Yu
Dr Yanguang Yu
Turbine machinery has an extraordinary wide range of applications in the aviation, aerospace, automotive, energy and many other industries. The turbine blade is one of the most important parts of turbine machinery, and the characteristic parameters, pressure ratio of the engine and rotating speed of the turbine are all related to the shape and size of blades. Therefore, the profile measurement of turbine blade is an essential issue in the blade machining processing, however, it is difficult and particular to establish the profile measurement of turbine blade because of its complicated shapes and space angles of the blades, and the …
The Fourier Spectrum Analysis Of Optical Feedback Self-Mixing Signal Under Weak And Moderate Feedback, Xiaojun Zhang, Jiangtao Xi, Yanguang Yu, Joe F. Chicharo
The Fourier Spectrum Analysis Of Optical Feedback Self-Mixing Signal Under Weak And Moderate Feedback, Xiaojun Zhang, Jiangtao Xi, Yanguang Yu, Joe F. Chicharo
Dr Yanguang Yu
The spectrum characteristics of self-mixing signals observed in optical feedback self-mixing interferometry (OFSMI) is studied in this paper. The purpose is to provide guidance for the design of pre-processing techniques for eliminating noise or disturbance. The influence of two important parameters of the OFSMI system on the spectrum, that is, the optical feedback factor and the linewidth enhancment factor, are measured by means of Discrete Fourier transform (DFT). The simulated results show that, at a weak feedback, the OFSMI signals are strictly band limited in nature, with the cut-off frequencies being the vibration frequency and the fringe frequency respectively. Also …