Gao Zhanfeng

Strain monitoring of railway bridges using optic fiber sensors

Purpose – The purpose of this article is to suggest that Fraby‐Perot optic sensor is a practical measurement gage to monitor the strain of great structures such as railway bridges.Design/methodology/approach – A remote strain monitoring system based on F‐P optic fiber and virtual instrument is designed to monitor the strains of a railway bridge.Findings – The application results show that the Fraby‐Perot optical fiber sensors can accurately measure strain and they are suitable for the long‐term and automatic monitoring. In addition, the system has several advantages over conventional structural instruments including fast response, ability of both static and dynamic monitoring, absolute measurement, immunity to interferences such as lightning strikes, electromagnetic noise and radio frequency, low attenuation of light signals in long fiber optic cables.Practical implications – Health monitoring of structures is getting more and more recognition all over the world because it can minimize the cost of reparat...

Network Sensor and Its Application in Structure Health Monitoring System

Network sensor is a new sensing technique in which sensor signal is transferred into digital signal and transmitted on the basis of network protocol. The network sensor provides for the consolidation of analog signal conditioning and digital signal processing functions at the sensor, which results in system cost reductions, high reliability and improved performance. In order to improve the disadvantage of the traditional structure safety monitoring system, the principle and realization of a novel network sensor designed with A/D converter ADS8321, microprocessor Rabbit3000 and TCP/IP protocol are introduced. The structure health monitoring system (SHMS) based on network technique is discussed as well. The results show that the network sensor has the characteristics of great applicability, flexibility and high reliability. It represents the new development direction of the structure health monitoring system

Estimating algorithm of angular velocity on assisted motor

Angular velocity of assisted motor is the switch criteria for different control models of EPS. Reasonable estimation for angular velocity not only reduces the hardware configuration of EPS and decreases the hardware cost of the system, but also increases the reliability of the system. H∞ control theory was applied to angular velocity estimation of assisted motor. An H∞ filter was designed. The measurement noise from voltage sensor and current sensor was selected as exogenous disturbances. The estimated error for angular velocity was determined as adjusted output. The filter was simulated under simulink environment of MATLAB. The simulation result shows that the estimating algorithm is feasible.

Applications of ANNs in Geotechnical Engineering

Artificial neural networks (ANNs) were developed very quickly and applied very widely in recent years due to their strong ability to solve the nonlinear problems. The artificial neural network-based method was also widely applied to the geotechnical engineering. The complexity of the geotechnical engineering problems because of the strong nonlinear relationship between knows and unknowns of the problems can be mapped very well by artificial neural networks. Researches on the application of artificial neural network in geotechnical engineering are reviewed and appraised in this paper. All the networks mentioned are trained with the back-propagation algorithm which is widely used by a great number of researchers. Research reveals that the method is feasible and it will be interested for more geotechnical engineers.

A Networked Data Acquisition System Based on the MSC1210

In this paper, a new high precision A/D Converter MSC1210 which integrates 8052 Micro-controller and Flash Memory is presented at first. Then a networked data acquisition system based on the technology of Ethernet and RS-485 is designed. The communication between remote monitoring center and host computer is based on TCP/IP protocol through Ethernet, and the communication between host computer and numerous MSC1210s is based on RS-485 serial protocol. The system has characteristics of long-distance transmission, flexible configuration, good reliability and real-time performance. The scheme can be used in many fields, such as metallurgy, chemistry, colliery and etc, where remote data acquisition on large-scale system is needed.

Synthesis the structure of the amplitude-sampled fiber Bragg gratings by Fourier transformation

Using the simple inverse Fourier transformation, we can design the index modulation structure of the sampled period of the sampled fiber Bragg gratings (FBGs). In this method the enable channels are identical wavelength operation while the unable channels are almost suppressed completely. The enable and unable channels can be established at will based on the applications. This technique is very useful for flexible design optics devices such as optical add and drop multiplexers (OADMs), and interleavers with dispersion and dispersion slope compensation.

Optimization of the interference spectrum of separated long-period fiber grating pair and its application for multi-channel isolation filter

The interference transmission spectrum of the cascaded long-period fiber gratings, between which inserted a section of fiber, is investigated. Analytic expressions for the interference spectrum are derived, from which insightful physical meanings can be seen, such as the fringe spacing dependences, the maximum peak loss dependences. Based on the design criteria, we used the Levenberg- Marquardt (LM) method to design a flattened spectrum with transmission loss of nearly 50%. A useful device of tunable multi-channel isolation filter was designed by cascading two such identical long period fiber gratings. This device has great potential to be used for wavelength-division-multiplexed optical communication systems.