Crossed grating stuck to metal surface was used as a strain sensor in the present work, and stress as well as strain were then investigated by accurately determining the change in the position of diffraction spot befo...Crossed grating stuck to metal surface was used as a strain sensor in the present work, and stress as well as strain were then investigated by accurately determining the change in the position of diffraction spot before and after deformed. A hardware testing system for linear CCD array, data gathering and processing was therefore developed for this purpose. Experimental results showed that the system has a good accuracy and can be used to measure stress and strain of metal surface in a real-time and quantitative manner.展开更多
An induced matching M in a graph G is a matching such that V(M) induces a 1-regular subgraph of G. The induced matching number of a graph G, denoted by I M(G), is the maximum number r such that G has an induced matchi...An induced matching M in a graph G is a matching such that V(M) induces a 1-regular subgraph of G. The induced matching number of a graph G, denoted by I M(G), is the maximum number r such that G has an induced matching of r edges. Induced matching number of Pm×Pn is investigated in this paper. The main results are as follows:(1) If at least one of m and n is even, then IM(Pm×Pn=[(mn)/4].(2) If m is odd, then展开更多
A novel tunable chirped fiber Bragg grating technology is proposed and simulated numerically by Matlab. If we adhere a uniform fiber grating with super magnetostrictive film and expose them in a non-uniform magnetic f...A novel tunable chirped fiber Bragg grating technology is proposed and simulated numerically by Matlab. If we adhere a uniform fiber grating with super magnetostrictive film and expose them in a non-uniform magnetic field, the period of the grating can be changed with the strain imposed on it by the magnetostrictive effect .The chirped characteristics can be tuned by changing the magnetic filed which is very flexible in designing.展开更多
A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of...A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of about 257.2 rad·s2/m and a resolution of 4.2×10-5 m/s2 for monitoring acceleration.Experimental results show that the phase-shift changes with the acceleration linearly.展开更多
A novel composite technique of orthogonally bonding carbon fiber-reinforced polymer （CFRP） strips and steel strips is proposed to improve the performance of reinforced concrete （RC） structures based on co-working ...A novel composite technique of orthogonally bonding carbon fiber-reinforced polymer （CFRP） strips and steel strips is proposed to improve the performance of reinforced concrete （RC） structures based on co-working of CFRP strips and steel strips. To verify the effectiveness of the method for strengthening RC two-way slabs, seven flat slabs with the dimensions of i 500 mm x 1 500 mm x 70 mm and an internal reinforcement ratio of 0.22% were prepared and tested until failure under concentrated loading, of which one was unstrengthened, one was strengthened with CFRP strips bonded to its soffit making a grid pattern （termed the CFRP grid）, and five were strengthened with a hybrid grid of CFRP strips and steel strips in two orthogonal directions （termed the CFRP-steel grid） to the bottom with steel bolt anchorage. The investigation parameters are the strengthening method, the strip spacing （150, 200, and 250 mm） and the layers of CFRP strips （one layer, two layers, and three layers of CFRP strips are applied for CFRP-steel grid）. The experimental results show that the strengthening RC two-way slabs with CFRP-steel grid are effective in delaying concrete cracking and enhancing the load-carrying capacity and deformability in comparison to the CFRP grid strengthening. The yield-line analysis model is proposed to predict the load-carrying capacity of the strengthened slabs. The prediction results are in good agreement with the experimental results.展开更多
The fiber Bragg grating （FBG） sensing technology is used to dynamically monitor multiple parameters of railway switch machine poles, including time of movement, direction and quantity of loading and locking force, a...The fiber Bragg grating （FBG） sensing technology is used to dynamically monitor multiple parameters of railway switch machine poles, including time of movement, direction and quantity of loading and locking force, and states of loading resistance. This paper presents the design and implementation of a railway switch pole strain on-line monitoring system based on the FBG stress-sensibilized monitor for a Siemens S700K switch machine. The ring shape FBG strain gauge and stress-sensibilized methods significantly increased the monitoring sensitivity. Installing approaches adapted the harsh environment in the railway application. The monitoring results showed the high sensitivity and high reliability of this monitoring system. This application provides a long-term and on-line detecting method which could meet railway switch condition monitoring demands of more than 100,000 switch machines in the country.展开更多
A fiber Bragg grating strain sensor,whose reflection bandwidth is insensitive to temperature,is presented.The cross-sec-tional area is designed to change linearly.Under axial stress,there is a linear relationship betw...A fiber Bragg grating strain sensor,whose reflection bandwidth is insensitive to temperature,is presented.The cross-sec-tional area is designed to change linearly.Under axial stress,there is a linear relationship between stress and average strain.Experimental results show that when temperature increases,reflection center wavelength shifts to longer wavelength,and there is a good linear relationship between center wavelength and temperature.When stress increases,reflection center wavelength shifts to longer wavelength,and reflection bandwidth increases.There are good linear relationships between reflection center wavelength and stress as well as reflection bandwidth and stress.展开更多
文摘Crossed grating stuck to metal surface was used as a strain sensor in the present work, and stress as well as strain were then investigated by accurately determining the change in the position of diffraction spot before and after deformed. A hardware testing system for linear CCD array, data gathering and processing was therefore developed for this purpose. Experimental results showed that the system has a good accuracy and can be used to measure stress and strain of metal surface in a real-time and quantitative manner.
文摘An induced matching M in a graph G is a matching such that V(M) induces a 1-regular subgraph of G. The induced matching number of a graph G, denoted by I M(G), is the maximum number r such that G has an induced matching of r edges. Induced matching number of Pm×Pn is investigated in this paper. The main results are as follows:(1) If at least one of m and n is even, then IM(Pm×Pn=[(mn)/4].(2) If m is odd, then
文摘A novel tunable chirped fiber Bragg grating technology is proposed and simulated numerically by Matlab. If we adhere a uniform fiber grating with super magnetostrictive film and expose them in a non-uniform magnetic field, the period of the grating can be changed with the strain imposed on it by the magnetostrictive effect .The chirped characteristics can be tuned by changing the magnetic filed which is very flexible in designing.
基金supported by the Science Fund for Young Scholars of Heilongjiang University,China(No.QL200901)
文摘A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of about 257.2 rad·s2/m and a resolution of 4.2×10-5 m/s2 for monitoring acceleration.Experimental results show that the phase-shift changes with the acceleration linearly.
基金The National Natural Science Foundation of China(No.51108355)
文摘A novel composite technique of orthogonally bonding carbon fiber-reinforced polymer （CFRP） strips and steel strips is proposed to improve the performance of reinforced concrete （RC） structures based on co-working of CFRP strips and steel strips. To verify the effectiveness of the method for strengthening RC two-way slabs, seven flat slabs with the dimensions of i 500 mm x 1 500 mm x 70 mm and an internal reinforcement ratio of 0.22% were prepared and tested until failure under concentrated loading, of which one was unstrengthened, one was strengthened with CFRP strips bonded to its soffit making a grid pattern （termed the CFRP grid）, and five were strengthened with a hybrid grid of CFRP strips and steel strips in two orthogonal directions （termed the CFRP-steel grid） to the bottom with steel bolt anchorage. The investigation parameters are the strengthening method, the strip spacing （150, 200, and 250 mm） and the layers of CFRP strips （one layer, two layers, and three layers of CFRP strips are applied for CFRP-steel grid）. The experimental results show that the strengthening RC two-way slabs with CFRP-steel grid are effective in delaying concrete cracking and enhancing the load-carrying capacity and deformability in comparison to the CFRP grid strengthening. The yield-line analysis model is proposed to predict the load-carrying capacity of the strengthened slabs. The prediction results are in good agreement with the experimental results.
基金The authors gratefully acknowledge the financial support of this work by the National Science Foundation of China, Numbered 61290311. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author（s） and source are credited.
文摘The fiber Bragg grating （FBG） sensing technology is used to dynamically monitor multiple parameters of railway switch machine poles, including time of movement, direction and quantity of loading and locking force, and states of loading resistance. This paper presents the design and implementation of a railway switch pole strain on-line monitoring system based on the FBG stress-sensibilized monitor for a Siemens S700K switch machine. The ring shape FBG strain gauge and stress-sensibilized methods significantly increased the monitoring sensitivity. Installing approaches adapted the harsh environment in the railway application. The monitoring results showed the high sensitivity and high reliability of this monitoring system. This application provides a long-term and on-line detecting method which could meet railway switch condition monitoring demands of more than 100,000 switch machines in the country.
基金supported by the National Natural Science Foundation of China(Nos.60837002and61177069)the Ph.D.Programs Foundation of Ministry of Education of China(No.20090009110003)the Fundamental Research Funds for the Central Universities(No.2011YJS214)
文摘A fiber Bragg grating strain sensor,whose reflection bandwidth is insensitive to temperature,is presented.The cross-sec-tional area is designed to change linearly.Under axial stress,there is a linear relationship between stress and average strain.Experimental results show that when temperature increases,reflection center wavelength shifts to longer wavelength,and there is a good linear relationship between center wavelength and temperature.When stress increases,reflection center wavelength shifts to longer wavelength,and reflection bandwidth increases.There are good linear relationships between reflection center wavelength and stress as well as reflection bandwidth and stress.
