Characteristics of Smart Concrete with Fiber Optical Bragg Grating Sensor

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.

NOVEL FIBER GRATING SENSOR DEMODULATION TECHNIQUE BASED ON OPTICAL WAVELET FILTERING

The optical wavelet filter is designed. It can filter and choose frequency swiftly. It can realize demodulation of distributed fiber Bragg grating（FBG） measurement system. Its scanning resolution and scanning period depend on wavelet function. Wavelet function is controlled by computer. Compared to conventional scan filter, optical wavelet filtering has some advantages such as simple structure, high scan frequency, high resolution and good linearity. At last, the error of optical wavelet filter scanning procedure is analyzed. Scanning step length refers to the shifting of optical wavelet window＇s central frequency. It affects system precision directly. If scanning step length is different, the measured signal is different. The methods of reducing step length guarantee scanning periodic time are presented.

Multi-Wavelength Optical Packet Routing Technologies Based on Superstructured Fiber Bragg Gratings

A WDM compatible Edge-to-Edge Self-Routed optical packet switched network that simplifies the optical processing is proposed. The system employs all-optical packet label generation and recognition using coded superstructured Fiber Bragg gratings.

A novel durable intelligent fiber reinforced polymer anchor with embedded optical fiber Bragg grating sensors

Anchors are the key members of the geotechnical anchorage engineering, it is urgent to monitor their behavior in service for preventing the potential risks. This paper proposes a novel durable intelligent fiber reinforced polymer （FRP） anchor to understand the behavior of the anchor in the field application. Series of optical fiber Bragg grating （FBG） sensors were embedded into the central axis along the anchor to sense itself axial strain variations. An evolution model of axial strain was also developed to evaluate the behavior along the anchor. A demonstration test was carried out to test its self-sensing properties in the laboratory. The experimental results indicated that the embedded FBG sensors monitored the behavior, e.g. axial strairl/interfacial damage evolutions along the anchor and displacement/applied load at the pulling end effectively, without influence from the interfacial compression and slip effects.

Optical Properties of High Sensitivity Fiber Bragg Grating on Temperature Sensor

In this paper, the spectrum shift properties of the center reflection wavelength detected to be based on the FBG sensor with ambient temperature change. The basic theoretical methods and numerical simulation for the spectral properties of uniform Bragg grating is analyzed by using coupling mode theory which is optical properties of high sensitivity fiber Bragg grating on temperature sensor in accordance with experiment.

Field measurement of strain response for typical asphalt pavement

In order to reveal the changing law of the mechanical response of asphalt pavements under the action of vehicle load and provide references for the design of durable pavements,three typical asphalt pavement structures with flexible base(S1),combined base(S2),and semi-rigid base(S3)were selected to perform field strain tests under static and dynamic load using the fiber Bragg grating optical sensing technology.The changing characteristics of the strain field along the horizontal and depth directions of pavements were analyzed.The results indicate that the most unfavorable asphalt pavement layers were the upper-middle surface layer and the lower base layer.In addition,the most unfavorable loading positions on the surface layer and the base layer were the center of wheel load and the gap center between two wheels,respectively.The most unfavorable layer of the surface layers gradually moved from the lower layer to the upper layer with the increase of base layer modulus.The power function relationships between structural layer strain and vehicle speed were revealed.The semi-rigid base asphalt pavement was the most durable pavement type,since its strain value was lower compared to those of the other structures.

An applicable calorimetric method for measuring AC losses of 2G HTS wire using optical FBG

We present a new calorimetric method for measuring alternative current(AC)losses of high-temperature superconducting(HTS)tapes by optical fiber Bragg grating(FBG),which is particularly well suited for the AC loss measurement of Re BCO wires,so-called the second generation(2G)HTS wires.Compared with conventional calorimetric methods,the suggested method is both free of electromagnetic disturbance,magnetic field,and fast as well as simple.Self-field AC losses are measured by the optical FBG method and the conventional lock-in-amplifier(LIA)technique,respectively.The results show that the measured AC loss is in good agreement with those measured by the electric method,thus the presented calorimetric method would be available for measuring the AC loss of 2G wire and is expected to be generalized for the measurement of AC loss or thermal performances of HTS bulk.

Broken Wires Diagnosis Method Numerical Simulation Based on Smart Cable Structure

The smart cable with embedded distributed fiber optical Bragg grating （FBG） sensors was chosen as the object to study a new diagnosis method about broken wires of the bridge cable. The diagnosis strategy based on cable force and stress distribution state of steel wires was put forward. By establishing the bridge-cable and cable-steel wires model, the broken wires sample database was simulated numerically. A method of the characterization cable state pattern which can both represent the degree and location of broken wires inside a cable was put forward. The training and predicting results of the sample database by the back propagation （BP） neural network showed that the proposed broken wires diagnosis method was feasible and expanded the broken wires diagnosis research area by using the smart cable which was used to be only representing cable force.