A twisted fiber optic sensor based on intensity modulation is described. The principle and structure of the sensor and the choice of steel strand modules are introduced. The sensor is used to determine the tensile str...A twisted fiber optic sensor based on intensity modulation is described. The principle and structure of the sensor and the choice of steel strand modules are introduced. The sensor is used to determine the tensile strain and distribution. The experimental results show that the change of the transferring light power has an approximate linear relation with the outer force. The intelligent steel strands with this kind of sensor will have a good application in monitoring the concrete crack and deformation distribution in huge structures such as dams and bridges.展开更多
Based on the advantages of the fiber Bragg grating sensing technology,this paper presents a principle of a novel smart concrete with fiber optical Bragg grating sensor,analyses the theory and characteristics,illustrat...Based on the advantages of the fiber Bragg grating sensing technology,this paper presents a principle of a novel smart concrete with fiber optical Bragg grating sensor,analyses the theory and characteristics,illustrates the key technology and method to make the fiber Bragg grating sensor for the smart concrete,and proves the feasibility with experiments.The results indicate that the smart concrete with fiber Bragg grating sensors is feasible in the structure monitoring and damage diagnosing in the long run.展开更多
The key technology and main difficulty for optical fiber intrusion pre-warning systems （OFIPS） is the extraction of harmful-intrusion signals. After being processed by a phase-sensitive optical time-domain reflectom...The key technology and main difficulty for optical fiber intrusion pre-warning systems （OFIPS） is the extraction of harmful-intrusion signals. After being processed by a phase-sensitive optical time-domain reflectometer （O-0TDR）, vibration signals can be preliminarily extracted. Generally, these include noises and intrusions. Here, intrusions can be divided into harmful and harmless intrusions. With respect to the close study of signal characteristics, an effective extraction method of harmful intrusion is proposed in the paper. Firstly, in the part of the background reconstruction, all intrusion signals are first detected by a constant false alarm rate （CFAR）. We then reconstruct the backgrounds by extracting two-part information of alarm points, time and amplitude. This ensures that the detection background consists of intrusion signals. Secondly, in the part of the two-dimensional Kolmogorov-Smirnov （K-S） test, in order to extract harmful ones from all extracted intrusions, we design a separation method. It is based on the signal characteristics of harmful intrusion, which are shorter time interval and higher amplitude. In the actual OFIPS, the detection method is used in some typical scenes, which includes a lot of harmless intrusions, for example construction sites and busy roads. Results show that we can effectively extract harmful intrusions.展开更多
针对直流设备检修过程中的安全及效率问题,提出了一种基于光通信技术的直流设备检修二次隔离方法(Optical Communication based Secondary Isolation Method for Direct Current Equipment Maintenance,OCSIM)。该方法利用光纤传感技术...针对直流设备检修过程中的安全及效率问题,提出了一种基于光通信技术的直流设备检修二次隔离方法(Optical Communication based Secondary Isolation Method for Direct Current Equipment Maintenance,OCSIM)。该方法利用光纤传感技术实时监测设备状态,并通过光通信网络实现数据的高速传输;结合光电转换技术实现异常情况下的智能隔离控制。实验结果表明,OCSIM能准确监测温度等关键参数,数据传输时延满足实时性要求,隔离控制达到预期精度。展开更多
文摘A twisted fiber optic sensor based on intensity modulation is described. The principle and structure of the sensor and the choice of steel strand modules are introduced. The sensor is used to determine the tensile strain and distribution. The experimental results show that the change of the transferring light power has an approximate linear relation with the outer force. The intelligent steel strands with this kind of sensor will have a good application in monitoring the concrete crack and deformation distribution in huge structures such as dams and bridges.
文摘Based on the advantages of the fiber Bragg grating sensing technology,this paper presents a principle of a novel smart concrete with fiber optical Bragg grating sensor,analyses the theory and characteristics,illustrates the key technology and method to make the fiber Bragg grating sensor for the smart concrete,and proves the feasibility with experiments.The results indicate that the smart concrete with fiber Bragg grating sensors is feasible in the structure monitoring and damage diagnosing in the long run.
文摘The key technology and main difficulty for optical fiber intrusion pre-warning systems （OFIPS） is the extraction of harmful-intrusion signals. After being processed by a phase-sensitive optical time-domain reflectometer （O-0TDR）, vibration signals can be preliminarily extracted. Generally, these include noises and intrusions. Here, intrusions can be divided into harmful and harmless intrusions. With respect to the close study of signal characteristics, an effective extraction method of harmful intrusion is proposed in the paper. Firstly, in the part of the background reconstruction, all intrusion signals are first detected by a constant false alarm rate （CFAR）. We then reconstruct the backgrounds by extracting two-part information of alarm points, time and amplitude. This ensures that the detection background consists of intrusion signals. Secondly, in the part of the two-dimensional Kolmogorov-Smirnov （K-S） test, in order to extract harmful ones from all extracted intrusions, we design a separation method. It is based on the signal characteristics of harmful intrusion, which are shorter time interval and higher amplitude. In the actual OFIPS, the detection method is used in some typical scenes, which includes a lot of harmless intrusions, for example construction sites and busy roads. Results show that we can effectively extract harmful intrusions.
文摘针对直流设备检修过程中的安全及效率问题,提出了一种基于光通信技术的直流设备检修二次隔离方法(Optical Communication based Secondary Isolation Method for Direct Current Equipment Maintenance,OCSIM)。该方法利用光纤传感技术实时监测设备状态,并通过光通信网络实现数据的高速传输;结合光电转换技术实现异常情况下的智能隔离控制。实验结果表明,OCSIM能准确监测温度等关键参数,数据传输时延满足实时性要求,隔离控制达到预期精度。
