591 results about "Fiber bragg grating sensor" patented technology

The invention relates to a method and a system for monitoring and warning a pipeline landslide based on a fiber Bragg grating and a method for constructing the system. The monitoring is performed on four parts including landslide depth displacement, landslide surface displacement, thrust of landslide on a pipeline and pipeline strain, and comprises the steps of: firstly, inserting an inclinometerpipe (1) pasted with a fiber Bragg grating sensor from the landslide (13) to all potential sliding surfaces (15); secondly, embedding a slender concrete ground beam (2) of which two ends are fixedly restrained and the axial direction of a central reinforced bar (17) is stuck to a ground beam fiber Bragg grating sensor (20) in a direction vertical to the deformation direction of the landslide (13)below the surface of the landslide (13); thirdly, measuring the thrust of the landslide (13) on the pipeline by using an earth pressure cell fiber Bragg grating sensor (4) fixed on the pipeline (14);and fourthly, arranging monitoring sections on edges on two sides and the pipeline (14) in the center of the landslide (13), and uniformly arranging three pipe strain fiber Bragg grating sensors (3) on each monitoring section to monitor the axial strain of the pipeline (14).

A method and apparatus for monitoring changes in temperature or strain, using fiber Bragg gratings (FBG). The Method and apparatus is advantageously useful for the measurement under harsh conditions, such as by combustion turbines. The invention uses the wavelength shift which is caused by temperature or strain changes at the FBG and the changing of the refraction index of the fiber.

The invention relates to a method and a system for monitoring and warning pipeline landslide depth displacement and a method for constructing the system. The monitoring is divided into three parts including landslide depth displacement monitoring, monitoring of thrust of landslide on a pipeline and pipeline strain monitoring, and comprises the steps of: inserting an inclinometer pipe (1) pasted with a fiber Bragg grating sensor into the landslide (13), penetrating all potential sliding surfaces (15), extending the inclinometer pipe to a drilling hole 3 to 5m deep under a bedrock surface, and measuring the maximum tension strain born by the inclinometer pipe (1); measuring the front thrust of the landslide (13) on the pipeline by using a packaged earth pressure cell fiber Bragg grating sensor (4) fixed on the pipeline (14); and uniformly arranging pipeline (14) monitoring sections on edges on two sides of the landslide and the pipeline (14) in the center of the landslide (13), and uniformly arranging three pipe strain fiber Bragg grating sensors (3) on each monitoring section to monitor the axial strain of the pipeline (14).

The invention discloses a fiber bragg grating detection system device and method for detecting an anchoring force of an anchor rod. The fiber bragg grating detection system device consists of a fiber bragg grating sensor array, a fiber bragg grating anchor rod dynamometer, a fiber bragg grating demodulator, an optical cable and a computer, wherein the fiber bragg grating anchor rod dynamometer mainly comprises a plurality of fiber bragg grating sensors which are uniformly arranged on an annular elastic body arm and is arranged at the end part of the anchoring end of the anchor rod; meanwhile, the fiber bragg grating sensor array is distributed on a rod body of the anchor rod; the fiber bragg grating sensor array and the fiber bragg grating anchor rod dynamometer are respectively connected with the fiber bragg grating demodulator through the optical cable; and the fiber bragg grating demodulator is connected with the computer. According to the fiber bragg grating detection system device, the real-time detection on the stress of the anchor rod can be realized and the distributed measurement can be realized. The fiber bragg grating detection system device has the advantages of simple structure, convenience in mounting, high detection speed, long-distance monitoring, repeated use and easiness in protection and maintenance, and is widely applied to tunnels and slopes dug for coal mines, metallurgical mines, water conservancy, railways, roads and defense.

A method and device for sensing spatial variations and/or temperature variations in the locality of a fibre optic cable 1 is disclosed, wherein a broadband light source 47 is used to shine incident light onto a series of fibre Bragg gratings contained within zones A, B and C. Each zone contains a plurality of fibre Bragg gratings, the plurality of fibre Bragg gratings in any one zone having a substantially identical grating period, and the fibre Bragg gratings in the respective zones having different grating periods. The reflected light from each fibre Bragg grating is returned back down the fibre optic cable 1 and redirected via a 2×1 coupler 51 to a wavelength detection system 53 and a personal computer 63. The combination of wavelength detection system 53 and personal computer 63 allow analysis of the reflected light patterns, as well as providing a user interface which enables detection of the occurrence of a spatial and/or a temperature variation. The location of the said variation along the fibre optic cable 1 is advantageously detectable in terms of the particular zone A, B or C in which the said variation has been sensed.

The present invention discloses a fiber Bragg grating sensor system. The system according to the present invention comprises a wavelength tunable laser; a coupler for splitting output light from the wavelength tunable laser into two directions; a reference wavelength generating unit for receiving one directional output light from the coupler and for generating reference wave-lengths and an absolute reference wavelength in order to measure real-time wavelengths of the wavelength tunable laser; a fiber Bragg grating array for receiving the other directional output light from the coupler and for reflecting lights at each of the wave-lengths of the grating therein; a fiber grating wavelength sensing unit for measuring the time when each of the reflected lights from the fiber Bragg grating array is detected; a signal processing unit for figuring wavelength variation information with the use of the measured signals from the reference wavelength generating unit and for obtaining each of wavelengths of the detected lights from the fiber grating wavelength sensing unit; and a laser wavelength control feedback unit for applying AC voltage and DC voltage to the wavelength tunable filter in the wavelength tunable laser. Also, polarization dependency in the sensor system can be removed further installing a depolarizer or a polarization scrambler at the output end of the wavelength tunable laser. By applying the present invention, measurement accuracy of the grating sensor system 20 can be improved due to enhanced wavelength stability and suppression of polarization dependency. Therefore, the fiber Bragg grating sensor system based on the present invention would replace conventional structure/construction diagnosis systems.

The invention discloses a tunnel structure monitoring system and a tunnel structure monitoring method based on a distributed long-gauge fiber bragg grating. The system comprises distributed long-gauge fiber bragg grating sensors which are comprehensively distributed in a monitored range along the axial direction and the cross section of a tunnel; and longitudinal sedimentation of the tunnel and change conditions of various ring joints of the shield tunnel are monitored. The method comprises the following steps of arranging the distributed long-gauge fiber bragg grating sensors; and acquiring, transmitting and processing data. By the tunnel structure monitoring system and the tunnel structure monitoring method based on the distributed long-gauge fiber bragg grating, full-life monitoring on a tunnel structure in a construction period and a running period can be carried out, and longitudinal sedimentation, convergence deformation, joint deformation, duct piece internal force, strain and the like of the tunnel structure are dynamically monitored in real time.

The invention discloses an intelligent monitoring device for blades of a wind driven generator, which comprises a blade body, a power generator, a plurality of fiber bragg grating sensors and a fiber bragg grating signal analyzer. The blade body is mounted on a hub, the power generator is connected with the hub through a gear box and a spindle or is directly connected with the hub, the fiber bragg grating sensors are arranged on the blade body, and the fiber bragg grating signal analyzer is connected with the fiber bragg grating sensors through optical fibers and an optical fiber coupler. Besides, wavelengths of different fiber bragg grating sensors on the blade body are different, the fiber bragg grating signal analyzer measures amplitude and frequency relations of corresponding temperature, vibration and dependent variables of optical signals of different wavelengths to acquire information about vibration, dynamic balance, fatigue, deformation, load and damage of the blade body, thereby assisting working staff to handle accidents in time.

A gasification distributed temperature sensing system is disclosed. The sensing system includes a gasification vessel and a harsh environment fiber sensing cable package disposed within the gasification vessel, the sensing cable package includes a thermally conductive enclosure and at least one sensor cable including a distributed array of high-temperature fiber Bragg grating sensors, wherein the sensors are disposed and hermetically sealed within the thermally conductive enclosure.

The invention discloses a device for monitoring sleep and screening obstructive sleep apnea syndrome. The device comprises a sleep pillow and an FGB (Fiber Bragg Grating) sensor fixed at an appointed position of a bed, wherein the sleep pillow is internally provided with a reflective photoelectric sensor for monitoring an artery at the neck of a human body; a degree of blood oxygen saturation and a pulse wave signal are obtained by utilizing a photoelectric detecting principle; physiological information of blood oxygen and pulse wave of a testee can be obtained by virtue of amplifying, de-noising and separating the signal; the sleep pillow is internally provided with a 2*2 array microphone for collecting snore information when the person sleeps. The FGB pressure sensor fixed at the appointed position corresponds to the chest of the testee and is used for collecting respiration and movement signals of the human body. The device realizes non-contact type measurement for respiration, pulse, snore and movement signals of the testee, avoids influence from excessive electrodes to natural sleep of the testee when sleeping, can monitor sleep at a whole night of the testee, and provides important parameters for screening obstructive sleep apnea syndrome.

The invention discloses a plate structure impact monitoring method based on the fractal theory, and belongs to the technical field of impact monitoring of structure health monitoring. The method comprises steps as follows: step one, distribution of distributed fiber bragg grating sensors; step two, computation of box-counting fractal dimensions of the fiber bragg grating sensor impact response signals; step three, collection of the fiber bragg grating sensor impact response signals corresponding to sample impact points and box-counting fractal dimension computation; step four, collection of the fiber bragg grating sensor impact response signals corresponding to to-be-detected impact points and box-counting fractal dimension computation; step five, computation of x-axis coordinates of the to-be-detected impact points; step six, computation of y-axis coordinates of the to-be-detected impact points. According to a positioning algorithm, the positions of the impact points are judged through computation of the box-counting fractal dimensions of fiber bragg grating sensor impact response signal frequency spectrums, and the method has the characteristics of no need of a large number of prior knowledge, simplicity, rapidness, convenience, high practicability and the like.

The invention provides a fiber bragg grating sensor network based large-scale structure body deformation measurement method which aims to detect the condition of deformation of a large-scale structure body which is stressed by an external force or an internal force and real-timely monitors health conditions of the large-scale structure body. The fiber bragg grating sensor network based large-scale structure body deformation measurement method includes arranging a fiber bragg grating sensor network on a structure body to be detected, using a fiber bragg grating strain sensor to detect strain borne by the structure body, using a fiber bragg grating temperature sensor as temperature compensation of the strain sensor, interpolating detected disperse strain data into polynomials, performing twice integration, and bringing in initial conditions to obtain a deformation curve of the structure body. The fiber bragg grating sensor network based large-scale structure body deformation measurement method is mainly used for monitoring health conditions of the large-scale structure body and is suitable for large-scale networking; compared with traditional resistance strain gages for measuring strain of the structure body, the fiber bragg grating sensor network based large-scale structure body deformation measurement method has the advantages that defects that resistance strain gages are difficult to network and prone to be interfered by electromagnets and many shield cables are heavy are overcome.

The invention relates to an oil derrick stress data acquisition system based on a fiber Bragg grating sensor network, comprising an oil derrick stress strain field data test subsystem based on a distributed fiber Bragg grating sensor network, an oil derrick stress strain field data transmission and storage subsystem based on a serial port communication technology, and an oil well reliability evaluation subsystem based on OLE (Object Linkingand Embedding) technology and a Matlab calculation procedure. The three subsystems are connected with a fiber Bragg grating demodulator RS232 interface through an ADAM communication module by an industrial control computer; data in each channel in a fiber Bragg grating analyzer are read by adopting a Modbus communication protocol and an address distinguishing technology, and the field stress strain data arithmetic mean is filtered by the industrial control computer and then read into Access background database. The invention can rapidly and accurately evaluate the bearing capacity of land and ocean oil derricks and provide a great amount of full and accurate stress strain measurement data for the research and the evaluation of the safe and reliable operation of oil derricks.

The invention discloses an intelligent skin antenna electric compensation method based on an embedded fiber bragg grating. The method is characterized by comprising the steps that the fiber bragg grating is firstly embedded into a skin antenna structure, then sensed strain is converted into deformation displacement through a strain-displacement transfer matrix, finally the excitation current of a skin antenna is modified through sensed deformation displacement, and therefore the aim of the influence of compensation structure deformation on electric performance is achieved. The method has the advantages that the mechanical property of the skin antenna structure can be monitored in real time, health monitoring on the structure is achieved, and the problem that the electric performance of the skin antenna is lowered due to structural vibration and deformation on active service can be solved through the method. A fiber bragg grating sensor is light in mass and can be embedded into the structure, the pneumatic and invisible performance of an aircraft is not influenced, the fiber bragg grating sensor can be applied to the fields of airborne early warning aircrafts, warcrafts, unmanned aerial vehicles, invisible warships and the like, and the key technology for guaranteeing the reliable service of the performance of the skin antenna is achieved.

The invention provides an acoustic emission signal sensing system based on matching-type fiber Bragg grating (FBG), which aims to overcome limitation of the prior art and introduce an FBG sensor into the acoustic emission detection field. The acoustic emission signal sensing system comprises a broadband light source, a first fiber coupler, a second fiber coupler, the FBG, a tunable FBG filter, a first photoelectric detection circuit, a second photoelectric detection circuit, an analog-to-digital conversion circuit, an FBG array (FBGA) and a computer. The acoustic emission signal sensing system is mainly applied to structural safety monitoring of an aerospace plane and damage detection of important components, and has the advantages of high sensitivity, high response speed, long transmission distance and strong resistance to electronic interference; and compared with the power-type FBG acoustic emission sensing system, the acoustic emission signal sensing system based on the matching-type FBG provided by the invention has the beneficial effects that wavelength shift information is demodulated by a matching grating method so as to obtain information of an original acoustic emission wave, the detection object is optical wavelength rather than optical power, and optical wavelength information is not affected by optical power loss during the optical transmission process, thus the detection precision is higher, the resolution power is higher and the noise is smaller.

The invention discloses a fiber bragg grating low-frequency strain sensing demodulation system which comprises a narrow linewidth laser, an electro-optic/ acoustic optical modulator, a radio-frequency signal generator, an electro-optic phase modulator, a phase modulation signal generator, a coupler, a first fiber bragg grating sensor, a second fiber bragg grating sensor, a photoelectric detector, a data acquisition card and a strain demodulation module. The narrow linewidth laser provides a narrow linewidth laser source for the whole demodulation system, the electro-optic/ acoustic optical modulator modulates the laser source according to a chirp signal generated by the radio-frequency signal generator generating the chirp signal, and the electro-optic phase modulator performs phase modulation on the modulated laser source according to a sinusoidal modulation signal generated by the phase modulation signal generator generating the sinusoidal modulation signal. The coupler divides the laser source subjected to the phase modulation into two paths, the first fiber bragg grating sensor and the second fiber bragg grating sensor generate two paths of fiber bragg grating reflectance spectra under scanning of the two paths of the laser sources, the photoelectric detector performs photovoltaic conversion on the two paths of the fiber bragg grating reflectance spectra, the data acquisition card outputs two paths of optical fiber sensing digital signals, and the strain demodulation module is used for demodulating the two paths of the optical fiber sensing digital signals.

An actuator and sensor system (1) for composite structures, especially carbon-fiber reinforced plastic structures (10) with piezo-ceramic actuators, particularly for active vibration dampening and/or shape control purposes, as well as fiber Bragg grating sensors (30), particularly in the form of strain measurement sensors. The piezo-ceramic actuators are designed as piezo fiber modules (20a, 20b) and the fiber Bragg grating sensors (30) are at least partially embedded in the piezo fiber modules (20a, 20b).

The invention relates to an intelligent monitoring system for a flexible passive protective net. The intelligent monitoring system of the flexible passive protective net includes a dangerous source capture system, a signal processing system and an alarm system. Under a condition that the signal processing system determines that dangers happen in the protective net and/or the protective net reaches a dangerous degree, alarm signals and/or intelligence information are/is sent in one or more methods. Fiber bragg grating sensors are preinstalled on lower support ropes of the flexible passive protective net. Through monitoring the tension of the lower support ropes of the protective net, signals related with rock fall and breakage of the protective net are monitored in a real-time manner and then the signals are returned to a fiber bragg grating demodulator.