METHOD AND SYSTEM FOR IDENTIFYING CAVITY POSITION OF STRUCTURE BASED ON GLOBAL SEARCH

Abstract

A method and system for identifying a cavity position of a structure based on global search includes: step 1: using a structure requiring cavity position identification as a target area, arranging acoustic emission sensors at key positions of the target area, and acquiring actual travel time of signals between the acoustic emission sensors on site; step 2: constructing cavity models for the target area; and for each cavity model, tracking shortest paths of signal propagation between the acoustic emission sensors when each cavity model exists in the target area, to obtain theoretical travel time of the signals; and step 3: respectively calculating deviations between the theoretical travel time and the actual travel time of the signals between the acoustic emission sensors corresponding to each cavity model, and using a position of a cavity model corresponding to a minimum deviation as an identified cavity position in the target area.

Claims

1. A method for identifying a cavity position of a structure based on global search, comprising the following steps: step 1: using a structure requiring cavity position identification as a target area, arranging a plurality of acoustic emission sensors at key positions of the target area, and acquiring an actual travel time of signals between the plurality of acoustic emission sensors on site; step 2: constructing a plurality of cavity models for the target area; and for each of the plurality of cavity models, tracking shortest paths of a signal propagation between the plurality of acoustic emission sensors when each of the plurality of cavity models exists in the target area, to obtain a theoretical travel time of the signals between the plurality of acoustic emission sensors; and step 3: respectively calculating deviations between the theoretical travel time and the actual travel time of the signals between the plurality of acoustic emission sensors corresponding to each of the plurality of cavity models, and using a position of a cavity model corresponding to a minimum deviation as an identified cavity position in the target area.

2. The method according to claim 1, wherein in step 1, a method for arranging the plurality of acoustic emission sensors at the key positions of the target area is: arranging m acoustic emission sensors at different positions of the target area, m being an integer greater than or equal to 4.

3. The method according to claim 2, wherein all the m acoustic emission sensors have a pulse signal emission function.

4. The method according to claim 3, wherein in step 1, suppose that an active seismic source is S.sub.l, the active seismic source is an acoustic emission sensor transmitting a pulse signal, coordinates of the active seismic source are (x.sub.l, y.sub.l, z.sub.1), a moment at which the active seismic source transmits the pulse signal is t.sub.0.sup.l, coordinates of a k.sup.th acoustic emission sensor S.sub.k receiving the pulse signal is (x.sub.k, y.sub.k, z.sub.k), and an actual moment at which the pulse signal transmitted by S.sub.l is t.sub.0.sup.k, an actual travel time of the pulse signal between the acoustic emission sensor S.sub.l and the k.sup.th acoustic emission sensor S.sub.k is Δt.sub.0.sup.lk=t.sub.0.sup.k−t.sub.0.sup.l.

5. The method according to claim 4, wherein in step 2, a commonly used shortest path tracking method is used to track the shortest paths of the signal propagation between the plurality of acoustic emission sensors when each of the plurality of cavity models exists in the target area, to obtain the theoretical travel time of the signals between the plurality of acoustic emission sensors.

6. The method according to claim 4, wherein in step 2, a method for constructing the plurality of cavity models is: dividing the target area into blocks according to a specific ratio to obtain n block intersections, and using each of the n block intersections as a sample point to obtain a set including n sample points; traversing all the n sample points (x, y, z) in the set and all possible values of a radius r; and respectively constructing a spherical cavity model P.sub.xyzr with a radius of r by using each of the n sample points (x, y, z) as a sphere center, to obtain the plurality of cavity models in the target area, wherein the value of r is an integer multiple of a block length len, and is less than or equal to a maximum value among a length, a width, and a height of the target area.

7. The method according to claim 6, wherein when the spherical cavity model P.sub.xyzr exists in the target area, a tracked shortest path between the acoustic emission sensor S.sub.l transmitting the pulse signal and the k.sup.th acoustic emission sensor S.sub.k receiving the pulse signal is L.sub.xyzr.sup.lk, and a propagation speed of the pulse signal is V, a theoretical travel time of the pulse signal between the acoustic emission sensor S.sub.l and the k.sup.th acoustic emission sensor S.sub.k is: Δt.sub.xyzr.sup.lk=L.sub.xyzr.sup.lk/V.

8. The method according to claim 7, wherein in step 3, a deviation calculation formula is:
D.sub.xyzr=Σ.sub.l,k=1.sup.m(Δt.sub.xyzr.sup.lk−Δt.sub.0.sup.lk).sup.2.

9. A system for identifying a cavity position of a structure based on global search, comprising a plurality of acoustic emission sensors and a data processing module, wherein the plurality of acoustic emission sensors are respectively arranged in a target area, the target area comprises a plurality of different positions of the structure requiring a cavity position identification, and the plurality of acoustic emission sensors are configured to acquire an actual travel time of signals between the plurality of acoustic emission sensors on site; and the data processing module is configured to: first construct a plurality of cavity models for the target area; for each of the plurality of cavity models, track shortest paths of a signal propagation between the plurality of acoustic emission sensors when each of the plurality of cavity models exists in the target area, to obtain a theoretical travel time of the signals between the plurality of acoustic emission sensors; and finally respectively calculate deviations between the theoretical travel time and the actual travel time of the signals between the plurality of acoustic emission sensors corresponding to each of the plurality of cavity models, and use a position of a cavity model corresponding to a minimum deviation as an identified cavity position in the target area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG. 1 is a schematic diagram of arrangement of acoustic emission sensors according to an embodiment of the present invention; and

[0027] FIG. 2 is a flowchart according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0028] The present invention is further described with reference to the accompanying drawings and specific embodiments.

Embodiment 1

[0029] This embodiment discloses a method for identifying a cavity position of a structure based on global search, including the following steps:

[0030] step 1 using a structure requiring cavity position identification as a target area, arranging a plurality of acoustic emission sensors as shown in FIG. 1) at key positions of the target area, and acquiring actual travel time of signals between the acoustic emission sensors on site;

[0031] step 2: constructing a plurality of cavity models for the target area; and for each cavity model, tracking shortest paths of signal propagation between the acoustic emission sensors when each cavity model exists in the target area, to obtain theoretical travel time of the signals between the acoustic emission sensors; and

[0032] step 3: respectively calculating deviations between the theoretical travel time and the actual travel time of the signals between the acoustic emission sensors corresponding to each cavity model, and using a position of a cavity model corresponding to a minimum deviation as an identified cavity position in the target area.

Embodiment 2

[0033] Based on Embodiment 1, according, to this embodiment, in step 1, a method for arranging the plurality of acoustic emission sensors at key positions of the target area is: arranging m acoustic emission sensors at different positions of the target area, m being an integer greater than or equal to 4.

Embodiment 3

[0034] Based on Embodiment 2, according to this embodiment, all the acoustic emission sensors have a pulse signal emission function.

Embodiment 4

[0035] Based on Embodiment 3, according to this embodiment, in step 1, suppose that an active seismic source, that is, an acoustic emission sensor that transmits a pulse signal, is S.sub.l, coordinates of the active seismic source are (x.sub.l, y.sub.l, z.sub.l), a moment at which the active seismic source transmits the pulse signal is t.sub.0.sup.l, coordinates of a k.sup.th acoustic emission sensor S.sub.k that receives the pulse signal is (x.sub.ky.sub.k, z.sub.k) and an actual moment at which the pulse signal transmitted by S.sub.l is t.sub.0.sup.k, actual travel time of the signal between the acoustic emission sensor S.sub.l and the acoustic emission sensor S.sub.k is: Δt.sub.0.sup.lk=t.sub.0.sup.k−t.sub.0.sup.l.

Embodiment 5

[0036] Based on Embodiment 4, according to this embodiment, in step 2, a commonly used shortest path tracking method is used to track the shortest paths of signal propagation between the acoustic emission sensors when each cavity model exists in the target area, to obtain the theoretical travel time of the signals between the acoustic emission sensors.

Embodiment 6

[0037] Based on Embodiment 4, according to this embodiment, in step 2, a method for constructing the cavity models is as follows:

[0038] dividing the target area into blocks according to a specific ratio to obtain n block intersections, and using each block intersection as a sample point to obtain a set including n sample points; traversing all the sample points (x, y, z) in the set and all possible values of a radius r; and respectively constructing a spherical cavity model P.sub.xyzr with a radius of r by using each sample point (x, y, z) as a sphere center, to obtain all the cavity models in the target area, where the value of r is an integer multiple of a block length len, and is less than or equal to a maximum value among a length, a width, and a height of the target area.

Embodiment 7

[0039] Based on Embodiment 6, according to this embodiment, when the cavity model P.sub.xyzr exists in the target area, a tracked shortest path between the acoustic emission sensor S.sub.l that transmits a pulse signal and the acoustic emission sensor S.sub.k that receives the pulse is L.sub.xyzr.sup.lk, and a propagation speed of the pulse signal is V, theoretical travel time of the signal between the acoustic emission sensor S.sub.l and the acoustic emission sensor S.sub.k is: Δt .sub.xyzr.sup.lk=L.sub.xyzr.sup.lk/V.

Embodiment 8

[0040] Based on Embodiment 7, according to this embodiment, in step 3, a deviation calculation formula is:

D.sub.xyzr=Σ.sub.l,k=1.sup.m(Δ.sub.xyzr.sup.lk−Δt.sub.0.sup.lk).sup.2.

[0041] A process of the method in this embodiment is shown in FIG. 2.

Embodiment 9

[0042] This embodiment discloses a system for identifying a cavity position of a structure based on global search, including a plurality of acoustic emission sensors and a data processing module, where

[0043] the plurality of acoustic emission sensors are respectively arranged in a target area, that is, arranged at a plurality of different positions of a structure requiring cavity position identification, and are configured to acquire actual travel time of signals between the acoustic emission sensors on site; and

[0044] the data processing module is configured to: first construct a plurality of cavity models for the target area; for each cavity model, track shortest paths of signal propagation between the acoustic emission sensors when each cavity model exists in the target area, to obtain theoretical travel time of the signals between the acoustic emission sensors; and finally respectively calculate deviations between the theoretical travel time and the actual travel time of the signals between the acoustic emission sensors corresponding to each cavity model, and use a position of a cavity model corresponding to a minimum deviation as an identified cavity position in the target area.

[0045] The system in this embodiment uses the method for identifying a cavity position of a structure based on global search according to any one of the foregoing Embodiments 1 to 8 to identify the cavity position inside the structure.