Xiaoyang Huang

Fiber-Bragg-grating-based weigh-in-motion system using fiber-reinforced composites as the load-supporting material

A novel fiber Bragg grating (FBG)-based weigh-in-motion (WIM) system is introduced in order to achieve a better performance compared with the existing WIM systems. This novel WIM system uses the fiber-reinforced composite (FRC) as the load-supporting material in combination with the FBG technology. The sensor is designed as a multiply FRC laminate with the FBG embedded inside it. A theoretical model is developed to analyze the mechanism of this WIM system. Both static and dynamic tests are conducted to verify the system performance. With the extraordinary mechanical properties of the FRC, this novel WIM system has achieved larger dynamic range and higher sensitivity than prior works. The simple design of the system also reduces the engineering difficulties and overall costs.

Radio-propagation model based on the combined method of ray tracing and diffraction

In this paper, we consider UHF radio wave propagation in vegetated residential environments. The attenuating effects of trees as well as those due to diffraction over the buildings are investigated. A new radio wave propagation prediction model based on the combined method of ray tracing and diffraction (CMRTD) is proposed. A row of trees is modeled as a two-dimensional (2-D) cylinder. It is then represented by an equivalent phase object (EPO); a row of buildings is replaced by an absorbing screen. The position and size of the EPO as well as the amplitude and phase distributions of the input field at the EPO are determined by ray tracing. Next the scattered field is computed by the Kirchhoff diffraction theory. Among the numerical results are those of the scattering from a row of trees with circular or elliptic canopies and the scattering from a row of trees/buildings configuration. The calculations treat both plane- and cylindrical-incident waves. By comparing the results with those obtained from the exact eigenfunction expansion method, we show that the CMRTD is an accurate and efficient method to calculate the scattering from a 2-D cylinder. Moreover, the range of the validity of using the CMRTD to model the scattering from one row of trees is determined.

Propagation prediction in a vegetated residential area using the combined method of ray tracing and diffraction

A theoretical method - the combined method of ray tracing and diffraction (CM-RTD), based on geometric optics and Kirchhoff diffraction theory, is used to compute the intensity behind one row of trees/buildings. In this work, the two-dimensional cases in which a cylindrical wave or plane wave is normally incident upon a row of trees/buildings are discussed.

Theoretical study of sensing targets through the wall using ultra-wideband technology

This study investigates the modeling of through-wall sensing using ultra-wideband (UWB) signals. The combined method of ray tracing and diffraction (CMRTD) is employed to model and study the interaction between the UWB signal and the target. The result is obtained in frequency domain, and then transformed into time domain by use of inverse Fourier transform. Numerical results of scattering from a two-dimensional (2D) perfectly conducting circular cylinder are obtained and compared with those from the eigenfunction expansion method. Good agreements between the results are achieved. In addition, the attenuating effects of walls are considered and numerical result of scattering from a 2D perfectly conducting circular cylinder behind a homogeneous, single-layered dry wall is presented. The model can be easily extended to handle the dielectric target and the multiple-layered walls.

Photonic Bands in DNA Crystal-Based Frequency-Dependent Media

An eigenvalue equation for the wave number of an electromagnetic wave propagating in a photonic crystal containing frequency dependent material is presented.

Forward Modeling of Through-Wall-Sensing with Ultra-Wideband Signals using Finite-Difference Time-Domain Method

In this study, the finite-difference time-domain (FDTD) method is applied to simulate the through-wall-sensing (TWS) with ultra-wideband signals. Perfectly matched layer (PML) absorbing boundary conditions are used to absorb the outgoing wave. Scattering from two-dimensional (2D) metallic and dielectric cylinders for a 2D TE plane-incident wave are considered. In addition the scattering from targets behind walls are investigated

Experimental Study of Coupling Fibre-optic Vibration Sensor

The coupling fibre vibration sensor is a new kind of whole fibre-optic vibration apparatus. It used single-mode fibre-optic as the basic structure, In the awl fused pulling process, change its parameter. Making it more sensitive to the outside interference, and thus detect the signals. Since the fibre-optic have characteristic such as strong anti- electromagnetism interference, anti-corrosion, bear the heat temperature, gathers signal feeling and deliver in an integral whole. It will have a good prospect in the field of vibration analysis and engineering structure safety monitor.

Sensing targets behind the opaque structures based on the combined method of ray tracing and diffraction

The modeling of through-wall sensing using ultra-wideband (UWB) signals is considered. The combined method of ray tracing and diffraction (CMRTD) is employed to analyze the interaction between the UWB signal and the target. The result is obtained in frequency domain, and then transformed into time domain by use of inverse Fourier transform (IFT). Scattering from a two-dimensional (2D) perfectly conducting circular cylinder is calculated and the result is shown in agreement with that obtained from the eigenfunction expansion method. Furthermore, the attenuating effects of walls are considered based on the geometrical optics. Numerical results of scattering from a 2D perfectly conducting circular cylinder behind a homogeneous, single-layered wall are given in both graphical and tabular formats.

Modeling radiowave scattering by an elliptical cylinder and its applications in communications and imaging

The scattering of a normally incident plane wave from an infinitely long, elliptical cylinder is investigated using the combined method of ray tracing and diffraction (CMRTD). Both horizontally and vertically polarized incident plane waves are considered. The analytical solution is given for the case when the size of the elliptical cylinder is large compared to the wavelength of the incident field, which is applied to simulate scattering from one row of elliptical trees in radiowave propagation. The numerical simulation results are presented and discussed.