Zhao Xia Wu

Analysis of FBG Reflection Spectrum with PSO Algorithm

When the parameters were measured by using fiber Bragg grating (FBG) in practice, there were some parameters hard to measure, which would influenced the reflective spectral of FBG severely, and make the characteristic information harder to be extracted. Therefore, particle swarm optimization algorithm was proposed in analyzing the uniform force reflective spectral of FBG. Based on the uniform force sense theory of FBG and particle swarm optimization algorithm, the objective function were established, meanwhile the experiment and simulation were constructed. And the characteristic information in reflective spectrum of FBG was extracted. By using particle swarm optimization algorithm, experimental data showed that particle swarm optimization algorithm used in extracting the characteristic information not only was efficaciously and easily, but also had some advantages, such as high accuracy, stability and fast convergence rate. And it was useful in high precision measurement of FBG sensor.

VLC-LED Receiver Condenser with Optimized CPC

In order to enhance the signal intensity of VLC-LED receiver, this paper describes a receiver condenser which is designed based on optimized CPC (compound parabolic concentrator) by using a truncated method, for achieving the aim of boosting receiver’s ability of gathering light and enhancing signal intensity. The Monte Carlo-ray tracing simulation results shows that in the VLC-LED system, the optimized CPC condenser has those advantages, such as higher concentration ratio, larger concentrate light deviation angle.

FBG Concentration Chemical Sensor with Three Layer Structure

FBG concentration chenical sensor with three layer structure is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is obtained. And the relationships between the concentration and the shift of Bragg wavelength of sucrose, ethanol, and Nacl solution are achieved. Finally the shifts of the Bragg wavelength with the external concentration are obtained by experiments.

The Multi-Channel Filter Based on Photonic Crystal with Circular Resonant Cavity

A photonic crystal model with circular resonant cavity is reported in order to achieve high efficiency and multi-channel filtration. Design a multi-channel filter based on its transmission properties. The distributions of the light energy of different wavelengths are given. As a result, the photonic crystal with circular resonant cavity has output efficiency of 75.5%99% and 100% when the wavelength is 1447nm1535nm and 1628nm. As the dielectric constant increases, the output wavelengths change. So, we can use this method to adjust the output wavelengths. Meanwhile, when the centre wavelength is 1447nm and 1535nm the multi-channel filter can output in different directions.

Characteristics of 2D Cylindrical Photonic Crystals Band Gap with Square Lattice

The structure of two-dimensional (2D) photonic crystals (PCs) with square lattice is proposed in this paper, and researches on characteristics of photonic band gap (PBG) are conducted using finite difference time domain (FDTD) method, then the effects of the dielectric constant and the radius of dielectric rods on band gap are analysed, dielectric rods in air (rods/air). The research results indicate that in the case of TE and TM polarization mode, the difference value of dielectric constant of medium and dielectric rods affects forming PBG.The band gap broadens with the difference value increasing. Whats more, the complete band gap (CBG) appears in range of large rods radius structure when dielectric constants of rods are smaller than that of medium.

Bridge Finite Element Model Updating Based on Uniform Design and Response Surface Method

An accurate finite element model is a necessity for analyzing the bridges health status. The uniform design combined with response surface finite element model updating method is proposed in this paper. The error of data obtained from updating model is less than 3% by contrasting static load test data in Shihe Bridge.The result shows that the updating model has a good fit with the actual bridge.

Two Dimensional Photonic Filter with a Circular Resonant Cavity

A new type of the two dimensional photonic filter which includes two in-line waveguides and a circular ring resonant cavity is presented in this paper. By using Finite Difference Time Domain (FDTD) method, we calculated and demonstrated the broadband frequency response of the filter and analyzed the impact of changing the dielectric constant of the inner rods on the transmission characteristics of the filter. Compared with the transmission characteristics of a micro-cavity,our numerical results show that such a filter can transmit multiple narrowband signals simultaneously. The number of the passbands of the filter increases with the rings of inner dielectric rods in the cavity. The center wavelength of the passbands can be tuned by adjusting the dielectric constant of the whole rods and inner rods without changing the size of the cavity..

The Swing Control of Cranes with Variable Rope Length Based on Linear Time Varying System Theory

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.

Theory Analysis of FBG Characteristics under 3D Homogeneous Stress Field

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.

Design Practical FBG Sensor Applied to Bridge Health Monitoring

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 systems 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.