Papers by Author: Zhao Xia Wu

Abstract: FBG sensing characteristics and model under three-dimensional stress are studyed in this paper. Theory analysis indicates that the reflection spectra of FBG is gradually splitted into two resonance peaks with the increase of the load and the two resonance peaks have a linear relation to the load. The difference of the wavelength sensitivity of the two directions of FBG is much less than the conditions of FBG only under transverse force, that is to say, the axial force plays a leading role in the shift amount of center wavelength.

Abstract: In this paper, following the state-feedback stabilization for time-varying systems proposed by Wolovich, a controller is designed for the overhead cranes with a linearized parameter-varying model. The resulting closed-loop system is equivalent, via a Lyapunov transformation, to a stable time-invariant system of assigned eigenvalues. The simulation results show the validity of this method.

Abstract: In this paper,the transveral force on uniform FBG is specially analyzed according to the couple-mode theory and the corresponding mathematical model is established. Studies show that when the FBG under local transverse force, the length of pressure has no effect on the reflection spectrum. The wavelength of the reflection spectrum splitting point and lateral force possessed a direct proportional linear correlation, and has periodicity at the same time. The split point reflectivity and the force position approximately have hyperbolic tangent relationship.

Abstract: In this paper how to generate respiratory flow that has fractal signal feature is introduced. Physiological signal have fractal feature have been verified by many researchers, such as heart beat rate, interbreath interval. Mechanical ventilators are used to provide life support for patients with respiratory failure. But these machines can damage the lung, causing them to collapse. On the other hand, fractal feature can be used as an indication of health situation; as a result in patient simulation the physiological signal should also have fractal features. The fractal feature is generated by fractional Brownian motion simulation. The fractal dimension is decided by Hurst exponent in routine. The algorithm is realized by R language and result is input into LabVIEW which have friendly interface and easy for simulation control usage. The method can be used in design of mechanical ventilator and medical patient simulator.

Abstract: Characteristic information of FBG reflection spectra changes because of the existence of demodulation system error in the actual demodulation. The analysis of spectra for FBG under axial uniform force based on particle swarm optimization is given in this paper. Objective function is established and force experiments and numerical simulation of fiber Bragg grating have been made. The characteristic information of FBG reflection spectra under axial uniform force is extracted and theoretically reconstructed. The results show that, the improved particle swarm algorithm in fiber grating reflection spectra analysis is feasible. Also, the method has other characteristics such as high accuracy, good stability and fast convergence speed.

Abstract: FBG sensing character and model under three-dimensional stress are studyed in this paper. FBG center wavelength shifts of the two polarization directions are different and the shifts are determined by the changes of refractive index and the axial stain. The experiment indicates that the resonance peak wavelength shift amounts of the two directions are proportional to the transverse load.

Abstract: Monitoring systems based on fiber optic technology have proved to exhibit meaningful benefits when compared with the current solutions of an electricnature. A novel low cost sensing system for measuring temperature, strain and pressure based on practical fiber Bragg grating (FBG) to be embedded into concrete is given in this paper. At the same time, the main principles of multi-parameter are introduced. The wavelength scanning demodulation system based on continuous wave tunable frequency is designed. The practical FBG sensors have been successfully used in monitoring cable-stayed bridge’s health monitoring. The system's conception, the adopted sensors network architecture, and the practical installation of a monitoring system based on FBG sensors are discussed. The experimental results indicate that practical FBG sensors can monitor the structure parameters for a long time, as well as have higher stability.