CN113776691B - Distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection - Google Patents
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 98
- 239000003245 coal Substances 0.000 title claims abstract description 40
- 238000005553 drilling Methods 0.000 title claims abstract description 36
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- 238000001069 Raman spectroscopy Methods 0.000 claims abstract description 54
- 230000035772 mutation Effects 0.000 claims abstract description 18
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- 239000000835 fiber Substances 0.000 claims description 16
- 238000005259 measurement Methods 0.000 claims description 16
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- 230000008859 change Effects 0.000 claims description 8
- 238000009529 body temperature measurement Methods 0.000 abstract description 9
- 238000005516 engineering process Methods 0.000 description 6
- 238000012544 monitoring process Methods 0.000 description 5
- 230000002159 abnormal effect Effects 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
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- 239000002817 coal dust Substances 0.000 description 1
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- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/324—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres using Raman scattering
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- Y02A90/30—Assessment of water resources
Abstract
The invention belongs to the technical field of coal field fire source drilling detection, and particularly relates to a high-precision distributed optical fiber Raman sensing method for goaf coal field fire source drilling detection. The method comprises the following steps: s1, a calibration stage: placing the sensing optical fiber in a temperature field with constant temperature, transmitting a single pulse into the sensing optical fiber, and measuring Raman scattered light signals excited by the laser pulse at each position in the sensing optical fiber; s2, measuring: transmitting a single pulse into the sensing optical fiber, and measuring Raman scattered light signals excited by the laser pulse at each position in the sensing optical fiber; and S3, demodulating to obtain the temperature of the temperature mutation point in the sensing optical fiber. The invention can solve the problem of the traditional distributed optical fiber Raman sensing system that the temperature measurement precision of the system is reduced due to insufficient spatial resolution, and can be applied to the field of coal field fire source drilling detection.
Description
Technical Field
The invention belongs to the technical field of coal field fire source drilling detection, and particularly relates to a high-precision distributed optical fiber Raman sensing method for coal field goaf fire source drilling detection.
Background
Coal is an important industrial raw material and is still the most important energy resource at present. Spontaneous combustion of coal is a serious accident type which can occur in the process of coal exploitation, storage and transportation, is one of important problems which need to be solved worldwide, and can cause social and ecological unbalance if the coal is improperly handled. Particularly in high-gas mines, secondary disasters such as gas or coal dust explosion are extremely easy to occur due to coal spontaneous combustion disasters.
Spontaneous combustion fires of coal beds occur underground, and the concealment of fire sources brings great difficulty to fire extinguishment and temperature monitoring and measurement work. Therefore, in the treatment work of drilling and extinguishing fire in the fire-extinguishing area, the measurement and the monitoring of the drilling temperature and the formulation of the extinguishing scheme are effective technological means through the drilling temperature measurement. The borehole geothermal distribution may truly reflect the geothermal field characteristics of the mine. Drilling temperature measurement is commonly carried out in coal field logging, and the low-temperature field characteristics and the formation mechanism of the whole mining area can be comprehensively and objectively known by analyzing influence factors of the drilling temperature distribution curve. Because the distributed optical fiber Raman temperature sensing system is only sensitive to the physical quantity of temperature change, has the advantages of being distributed, electromagnetic interference resistant, corrosion resistant and the like, and is particularly suitable for detecting fire in coal field fire source drilling based on temperature mutation feature identification. At present, researchers at home and abroad have preliminarily applied the distributed optical fiber Raman sensing technology to coal field fire source drilling detection.
The temperature measurement precision is an important performance index of the distributed optical fiber Raman sensing technology, the monitoring capability of the system on the sudden change of the environmental temperature is reflected, and the index is important to the fire source detection of coal fields and roadway drilling areas based on the distributed optical fiber sensing technology. The existing distributed optical fiber Raman sensing system is limited by meter-level spatial resolution, so that temperature change information of a coal field tiny fire source area is submerged in environmental noise, temperature change characteristics generated by tiny hidden fire sources are difficult to identify, and a good opportunity for early discovery and early management is finally lost, so that serious safety accidents of coal mines are most likely to be caused, and secondary disasters are further caused. Therefore, in the field of safety monitoring for coal field fire source drilling detection, the technical bottleneck of system temperature measurement precision deterioration caused by meter-level spatial resolution limits the application of the distributed optical fiber Raman temperature measurement system.
The national standard of the line-type temperature-sensing fire detector is specially established in China, and a sensitive part with the length of 100mm at any section of the detector is required to rapidly monitor high-temperature change so as to timely and effectively early warn under the condition of small fire and even rapid temperature rise in a small range, thereby extinguishing the fire in a sprouting state. The distributed optical fiber temperature measurement technology can realize the sensing of the temperature at any point on the optical fiber, but the method is to detect the average value of the temperature in a section of area (in the size of the spatial resolution of the system), and the detection result of a heat source with the size smaller than the spatial resolution of the system (usually 1 m) is far smaller than the real temperature value, so that the existing Raman distributed optical fiber sensing method is difficult to be used for monitoring small-size fire sources.
Based on the above, a brand new temperature demodulation method is necessary to be invented, so that the problem that the temperature measurement accuracy of the system is reduced due to lower spatial resolution of the existing distributed optical fiber Raman sensing system is solved, and the drilling detection of the goaf coal field fire source can be realized.
Disclosure of Invention
The invention provides a distributed optical fiber temperature sensing method for drilling and detecting fire sources in a goaf of a coal field, aiming at solving the technical problem that the temperature measurement precision in the existing distributed optical fiber Raman sensing system is limited by the spatial resolution of the system in meter magnitude and the technical problem that the detection of the drilling and the hidden fire sources is difficult to realize in the goaf and a coal mine tunnel.
In order to solve the technical problems, the invention adopts the following technical scheme: a distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection adopts a sensing device comprising a pulse laser and a sensing optical fiber, wherein the sensing optical fiber (4) is paved in a goaf coal field drilling area, and the sensing method comprises the following steps:
s1, a calibration stage: placing the sensing optical fiber at a constant temperature T o Transmitting a single pulse into the sensing optical fiber, and measuring Raman scattered light signals excited by the laser pulse at each position in the sensing optical fiber;
s2, measuring: transmitting a single pulse into the sensing optical fiber, and measuring Raman scattered light signals excited by the laser pulse at each position in the sensing optical fiber;
s3, demodulation: calculating slope auxiliary coefficients of all the positions in the sensing optical fiber, and judging temperature abrupt change points in the sensing optical fiber; according to the Raman scattered light signals obtained through measurement in the calibration stage and the measurement stage, calculating to obtain the temperature of a non-mutation point in the sensing optical fiber, and according to the intensity of the Raman scattered light signals generated by the laser pulses in the sensing optical fiber and the temperature of the non-mutation point in the sensing optical fiber, which are measured at two adjacent sampling moments, demodulating to obtain the temperature of the temperature mutation point in the sensing optical fiber, and further obtaining the temperature information distribution along the sensing optical fiber; the temperature demodulation formula of the temperature mutation point is as follows:
wherein ,Δf1 and Δf2 Pulse starting points corresponding to the ith and (i+1) th sampling moments, respectivelyThe number of sampling points between the pulse end point positions and the sampling point number between the pulse end point positions, h is the Planck constant, k is the Boltzmann constant, deltav is the Raman frequency shift, T non-FUT Temperature of non-mutation point, L i and Li+1 Respectively represent the positions of the laser pulses at the ith and the (i+1) th sampling moments, phi slope Representing the slope assistance coefficient.
In the step S3, the calculation formula of the slope auxiliary coefficient is:
wherein ,φa (L i) and φa (L i+1 ) Respectively represent the measuring stage laser pulse at L i and Li+1 The intensity of the stimulated raman scattering signal at the location, phi a0 (L i ) Indicating the scaling stage laser pulse at L i Raman scattering signal intensity of the raman scattering signal intensity excited at the location;
the calculation formula of the non-mutation point temperature is as follows:
wherein ,φa0 (L) represents the raman scattering signal intensity excited by the laser pulse at the position of the sensing fiber L during the calibration phase; phi (phi) a (L) represents the intensity of the Raman scattering signal excited by the laser pulse at the position of the sensing fiber L during the measurement phase.
In the step S1 and the step S2, the collected raman scattered light signal is raman scattered anti-stokes light.
The sensing device further includes: the system comprises a wavelength division multiplexer, a photoelectric detector, a data acquisition card and a computer;
the laser pulses emitted by the pulse laser are sequentially incident to the sensing optical fiber after passing through the wavelength division multiplexer; the Raman scattered light generated in the sensing optical fiber is output by the wavelength division multiplexer and then detected by the photoelectric detector, and the detection signal is acquired by the data acquisition card and then sent to the computer.
The computer is used for demodulating according to the detection signal of the photoelectric detector to obtain the temperature information distribution along the sensing optical fiber.
The sensing device also comprises an amplifier, and the amplifier is used for amplifying the electric signal output by the photoelectric detector and then sending the electric signal to the data acquisition card.
The wavelength of the optical signal output by the pulse laser is 1550nm, and the wavelength of the wavelength division multiplexer is 1450nm/1550nm.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection, which is realized based on a distributed optical fiber Raman temperature demodulation principle of a slope auxiliary demodulation technology.
Drawings
FIG. 1 is a schematic structural diagram of a sensing device used in a distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of laser pulse transmission in an embodiment of the present invention;
in the figure: the device comprises a 1-pulse laser, a 2-wavelength division multiplexer, a 4-sensing optical fiber, a 5-avalanche photodetector, a 6-amplifier, a 7-data acquisition card, an 8-computer, a 9-temperature normal point and a 10-temperature abnormal point.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments; all other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, a schematic structural diagram of a sensing device used in a distributed optical fiber temperature sensing method for drilling and detecting fire sources in goaf of coal field according to an embodiment of the present invention is shown, where in this embodiment, the sensing device includes: the device comprises a pulse laser 1, a wavelength division multiplexer 2, a sensing optical fiber 4, a photoelectric detector 5, a data acquisition card 7 and a computer 8.
Specifically, as shown in fig. 1, a first port a of the wavelength division multiplexer 2 is connected with a signal output end of the pulse laser 1, and a second port b of the wavelength division multiplexer 2 is connected with one end of the sensing optical fiber 4; a third port c of the wavelength division multiplexer 2 is connected with the avalanche photodetector 5; the wavelength division multiplexer 2 is used for sending the optical signal output by the pulse laser 1 to the sensing optical fiber 4 and sending anti-stokes light in the back-scattered optical signal to the photoelectric detector 5; the photoelectric detector 5 is used for collecting anti-Stokes optical signals in the back scattering optical signals and converting the anti-Stokes optical signals into electric signals, the data acquisition card 7 is used for collecting the electric signals and sending the electric signals to the computer 8, and the computer 8 is used for demodulating according to the anti-Stokes signals to obtain information of the distributed abrupt temperature field along the sensing optical fiber 4. The sensing optical fiber 4 is laid in the goaf coal field drilling area.
Further, as shown in fig. 2, the distributed optical fiber raman sensing device for drilling and detecting a fire source in a coal field provided in this embodiment further includes an amplifier 6, where the amplifier 6 is configured to amplify an electrical signal output by the photodetector 5 and send the electrical signal to the data acquisition card 7.
Further, in this embodiment, the wavelength of the optical signal output by the pulse laser 1 is 1550nm, the wavelength of the wavelength division multiplexer 2 is 1450nm/1550nm, and the incident light emitted by the laser with the wavelength of 1550nm enters the wavelength division multiplexer from the port a of the wavelength division multiplexer; the b port is emitted and enters the sensing optical fiber 4, the wavelengths of the back-scattered anti-Stokes light are 1450nm respectively, the back-scattered anti-Stokes light returns to the wavelength division multiplexer 2 through the b port of the wavelength division multiplexer 2, and then the avalanche photodetector 5 is injected from the c port respectively.
Specifically, the distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection provided by the embodiment comprises the following steps:
s1, a calibration stage: the sensing optical fiber 4 is placed at a constant temperature T o A single pulse is emitted into the sensing fiber 4 and raman scattered light signals generated by the corresponding laser pulse at each location in the sensing fiber are measured.
In order to compensate the influence of parameters such as attenuation of the sensing fiber on the temperature demodulation result, in this embodiment, all the sensing fibers are required to be placed in a constant temperature field (T o ) And (3) performing a scaling process. In the calibration process, the intensity of the Raman scattering signal acquired based on single pulse is shown as formula (1).
in the formula ,T0 The temperature of the sensing fiber 4 for the calibration phase. Wherein L is i Is the position of the laser pulse at the ith sampling moment; k (K) a Is the coefficient related to the scattering cross section of the optical fiber, P is the incident power of the pulse light source, lambda a Is the optical frequency of anti-Stokes light, alpha 0 and αa The optical loss coefficients of the incident light and the anti-stokes light, respectively. R is R a Representing a temperature-dependent modulation function,
h is the Planck constant, k is the Boltzmann constant, deltav is the Raman frequency shift, and 13.2THz.
S2, measuring: a single pulse is emitted into the sensing fiber 4, and raman scattered light signals excited by the laser pulse at various positions in the sensing fiber 4 are measured.
S3, demodulation: calculating slope auxiliary coefficients of all the positions in the sensing optical fiber, and judging temperature abrupt change points in the sensing optical fiber; according to the Raman scattered light signals measured in the calibration stage and the measurement stage, the temperature of a non-mutation point in the sensing optical fiber 4 is calculated, and according to the intensity of the Raman scattered light signals generated by the laser pulse in the sensing optical fiber 4 and the temperature of the non-mutation point in the sensing optical fiber 4, which are measured at two adjacent sampling moments, the temperature of the temperature mutation point in the sensing optical fiber 4 is obtained through demodulation, and further the temperature information distribution along the sensing optical fiber 4 is obtained.
The measurement principle and demodulation principle of the embodiment of the present invention are explained below.
First, the measurement stage in this embodiment will be described in two stages.
Measurement phase 1: when the laser pulse is at the boundary position of the temperature normal point 9 and the temperature abnormal point 10 in the sensing optical fiber 4, namely, when the laser pulse is about to leave the temperature normal point 9, the data acquisition card 7 acquires the Raman scattering signal light intensity phi at the ith sampling time a (L i ) Can be expressed as:
wherein ,Ra (T non-FUT )＝[exp(hΔν/kT non-FUT )-1] -1 ，R a (T FUT )＝[exp(hΔν/kT FUT )-1] -1 。
in the formula ,φa (L i ) For the ith sampling instant, i.e. laser pulse at L i At the position, the intensity, K, of the excited anti-Stokes light a Is the coefficient related to the scattering cross section of the optical fiber, P is the incident power of the pulse light source, lambda a Is the optical frequency of anti-Stokes light, h is the Planck constant, k is the Boltzmann constant, deltav is RamanThe frequency shift was 13.2THz. Alpha 0 and αa The optical loss coefficients of the incident light and the anti-stokes light, respectively. T (T) non-FUT Is the absolute temperature of the temperature normal point 9 in the sensing optical fiber 4, T FUT Is the absolute temperature of the temperature anomaly 10 in the sensing fiber 4. L (L) s1 Is the laser pulse at L i The starting point of the laser pulse at the position L f1 Is the laser pulse at L i End position point of laser pulse at position L m1 Is the boundary position of the temperature normal point 9 and the temperature abnormal point 10 in the sensing optical fiber.
Measurement phase 2: at the (i+1) th sampling time, the laser pulse is still at the boundary position of the temperature normal point 9 and the temperature abnormal point 10 in the sensing optical fiber 4, and the position of the laser pulse is marked as L i+1 The light intensity phi of the Raman scattering signal acquired by the data acquisition card 7 a (L i+1 ) Can be expressed as:
in the formula ,φa (L i+1 ) For measuring phase laser pulse at L i+1 The intensity of the excited anti-Stokes light at the location, L s2 Is the laser pulse at L i+1 The starting point of the laser pulse at the position L f2 Is the laser pulse at L i+1 End position point of laser pulse at position L m2 Is the boundary position (L m2 ＝L m1 )。
Next, the demodulation stage in this embodiment will be described in three stages, respectively.
Demodulation stage 1: the optical intensity ratio of the raman anti-stokes signals based on the formula (1) and the formula (2) can compensate the optical fiber attenuation and other coefficients, as shown in the following formula.
Demodulation stage 2: the optical intensity ratio of the raman anti-stokes signals based on the formula (2) and the formula (3) can compensate the optical fiber attenuation and other coefficients, as shown in the following formula.
Demodulation stage 3: based on the equation (4) and the equation (5), a slope assist coefficient φ can be calculated slope As shown in formula (6).
In formula (6), T o 、T non-FUT 、L i and Li+1 Is constant and therefore the slope assist coefficient phi slope And the temperature (T) of the sensing fiber area FUT ) The equation (6) is deformed by presenting a certain functional relation, and the equation (7) can be obtained.
wherein ,Δf1 Is the distance L s1 To L S2 Is a sampling point number of Deltaf 2 Is the distance L f1 To L f2 Is the Planck constant, k is the Boltzmann constant, deltav is the Raman frequency shift, T non-FUT Is the absolute temperature of the temperature normal point 9 in the sensing fiber in the measurement stage, so that based on the equation (7), the actual temperature information (T FUT )。
Further, in the present embodiment, the absolute temperature T of the temperature normal point 9 in the sensing fiber in the measuring stage non-FUT The calculation formula of (2) is as follows:
in formula (8), phi a0 (L) represents the scale phase laser pulse in sensingThe intensity of the Raman scattering signal excited at the position of the optical fiber L; phi (phi) a (L) represents the intensity of Raman scattering signal excited by the laser pulse at the position of the sensing fiber L in the measurement phase a0(L) and φa (L) can be obtained by measurement in a calibration stage and a measurement stage, respectively.
In summary, the invention provides a distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection, which is realized based on a distributed optical fiber Raman temperature demodulation principle of a slope auxiliary demodulation technology, and the distributed temperature mutation information along the sensing optical fiber is calculated through the light intensity slope data of anti-Stokes light of a slope auxiliary area along the sensing optical fiber, so that the spontaneous combustion hidden danger positions of goafs and coal mine roadway drilling areas are further positioned.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (6)
1. The distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection is characterized in that the adopted sensing device comprises a pulse laser (1) and a sensing optical fiber (4), the sensing optical fiber (4) is paved in a goaf coal field drilling area, and the sensing method comprises the following steps:
s1, a calibration stage: placing the sensing fiber (4) at a constant temperatureT o Transmitting a single pulse into the sensing optical fiber (4), and measuring Raman scattered light signals excited by the laser pulse at each position in the sensing optical fiber (4);
s2, measuring: transmitting a single pulse into the sensing optical fiber (4), and measuring Raman scattered light signals excited by the laser pulse at each position in the sensing optical fiber (4);
s3, demodulation: calculating slope auxiliary coefficients of all the positions in the sensing optical fiber, and judging temperature abrupt change points in the sensing optical fiber; according to the Raman scattering optical signals measured in the calibration stage and the measurement stage, calculating to obtain the temperature of a non-mutation point in the sensing optical fiber (4), and according to the Raman scattering optical signal intensity of the laser pulse generated by the sensing optical fiber (4) and the temperature of the non-mutation point in the sensing optical fiber (4) measured at two adjacent sampling moments, demodulating to obtain the temperature of the temperature mutation point in the sensing optical fiber (4), and further obtaining the temperature information distribution along the sensing optical fiber (4); the temperature demodulation formula of the temperature mutation point is as follows:
wherein ,Δf 1 and Δf 2 The number of sampling points between the pulse starting points and the number of sampling points between the pulse end point positions corresponding to the ith sampling time and the (i+1) th sampling time respectively,his a constant of planck, which is set to be the planck's constant,kis the boltzmann constant, deltav is the Raman frequency shift,T non-FUT temperature of non-mutation point, L i AndL i+1 respectively representing the positions of the laser pulses at the ith and the (i+1) th sampling moments,
representing a slope assist coefficient;
in the step S3, the calculation formula of the slope auxiliary coefficient is:
wherein ,φ a （L i） and φ a （L i+1 ) Dividing intoIndicating the measuring stage laser pulse at L i AndL i+1 the intensity of the stimulated raman scattering signal at the location,φ a0 （L i ) Indicating the scaling stage laser pulse at L i The intensity of the raman scattering signal excited at the location;
the calculation formula of the non-mutation point temperature is as follows:
wherein ,φ a0 （L) Representing the intensity of Raman scattering signals excited by the laser pulse at the position of the sensing optical fiber L in the calibration stage;φ a （L) Representing the intensity of the raman scattered signal excited by the laser pulse at the position of the sensing fiber L during the measurement phase.
2. The distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection according to claim 1, wherein in the step S1 and the step S2, the collected raman scattered light signal is raman scattered anti-stokes light.
3. The distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection of claim 1, wherein the sensing device further comprises: the device comprises a wavelength division multiplexer (2), a photoelectric detector (5), a data acquisition card (7) and a computer (8);
laser pulses emitted by the pulse laser (1) are sequentially incident to the sensing optical fiber (4) after passing through the wavelength division multiplexer (2); the Raman scattered light generated in the sensing optical fiber (4) is output by the wavelength division multiplexer (2) and then detected by the photoelectric detector (5), and a detection signal is acquired by the data acquisition card (7) and then sent to the computer (8).
4. The distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection according to claim 3, wherein the computer (8) is used for demodulating and obtaining temperature information distribution along the sensing optical fiber (4) according to detection signals of the photoelectric detector (5).
5. The distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection according to claim 3, wherein the sensing device further comprises an amplifier (6), and the amplifier (6) is used for amplifying an electric signal output by the photoelectric detector (5) and then sending the electric signal to the data acquisition card (7).
6. The distributed optical fiber temperature sensing method for coal field goaf fire source drilling detection according to claim 3, wherein the wavelength of an optical signal output by the pulse laser (1) is 1550nm, and the wavelength of the wavelength division multiplexer (2) is 1450nm/1550nm.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2515705A1 (en) * | 2003-02-12 | 2004-08-26 | Sensornet Limited | Method and apparatus for generation and transmission of high energy optical pulses for long range measurements |
| CN112556875A (en) * | 2020-12-01 | 2021-03-26 | 太原理工大学 | Distributed optical fiber Raman sensing system and method for gas pipe network leakage |
| CN113091946A (en) * | 2021-04-19 | 2021-07-09 | 太原理工大学 | Chaotic distributed optical fiber Raman temperature sensing device and method |
| CN113091947A (en) * | 2021-04-19 | 2021-07-09 | 太原理工大学 | ASE time domain correlation compression distributed optical fiber Raman temperature sensing device and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CA2515705A1 (en) * | 2003-02-12 | 2004-08-26 | Sensornet Limited | Method and apparatus for generation and transmission of high energy optical pulses for long range measurements |
| CN112556875A (en) * | 2020-12-01 | 2021-03-26 | 太原理工大学 | Distributed optical fiber Raman sensing system and method for gas pipe network leakage |
| CN113091946A (en) * | 2021-04-19 | 2021-07-09 | 太原理工大学 | Chaotic distributed optical fiber Raman temperature sensing device and method |
| CN113091947A (en) * | 2021-04-19 | 2021-07-09 | 太原理工大学 | ASE time domain correlation compression distributed optical fiber Raman temperature sensing device and method |
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