阅读说明：本技术 一种基于超声波快速识别物质的方法 (Method for rapidly identifying substance based on ultrasonic waves ) 是由 张建 陈晓静 李秋颖 于 2019-11-12 设计创作，主要内容包括：本发明涉及一种基于超声波快速识别物质的方法,具体包括以下步骤：(1)选取一个已知物质,已知物质的声阻抗值表示为Z<Sub>1</Sub>,待分辨的未知物质的声阻抗值表示为Z<Sub>2</Sub>；(2)使用换能器从已知物质向未知物质垂直发射超声波信号x(t),计算入射波信号的能量P<Sub>i</Sub>；(3)超声波发射信号经过所述交界面反射返回超声波反射信号y(t),计算反射波信号的能量P<Sub>r</Sub>,(4)根据已知物质的声阻抗值Z<Sub>1</Sub>、入射波信号的能量P<Sub>i</Sub>以及反射波信号的能量P<Sub>r</Sub>计算未知的声阻抗值Z<Sub>2</Sub>；(5)由于不同物质具有不同的声阻抗值,根据步骤(4)计算得到的未知物质的声阻抗值Z<Sub>2</Sub>可分辨出未知物质的具体物质名称。本发明通过发射超声波间接识别物质,避免了水下探测时不能测得声速或者密度而导致不能识别物质的问题。(The invention relates to a method for quickly identifying substances based on ultrasonic waves, which specifically comprises the following steps: (1) selecting a known substance having an acoustic impedance value expressed as Z 1 The value of the acoustic impedance of the unknown substance to be resolved is expressed as Z 2 (ii) a (2) Vertically transmitting an ultrasonic signal x (t) from a known substance to an unknown substance by using a transducer, and calculating the energy P of an incident wave signal i (ii) a (3) The ultrasonic emission signal is reflected by the interface and returns to the ultrasonic reflection signal y (t), and the energy P of the reflected wave signal is calculated r (4) the value of acoustic impedance Z according to the known substance 1 Energy P of incident wave signal i And energy P of the reflected wave signal r Calculating an unknown value of acoustic impedance Z 2 (ii) a (5) Because different substances have different acoustic impedance values, the acoustic impedance value Z of the unknown substance calculated according to the step (4) 2 The specific substance name of the unknown substance can be identified. The invention indirectly identifies the substance by transmitting ultrasonic waves, and avoids the problem that the sound velocity or density cannot be measured during underwater detection to cause the incapability of identifyingProblems with the substance.)

1. A method for rapidly identifying substances based on ultrasonic waves is characterized in that: the method specifically comprises the following steps:

(1) selecting a known substance and an unknown substance, and placing the known substance and the unknown substance together, wherein the acoustic impedance value of the known substance is expressed as Z₁The value of the acoustic impedance of the unknown substance to be resolved is expressed as Z₂；

(2) Vertically transmitting an ultrasonic signal x (t) from a known substance to an unknown substance using a transducer;

(3) calculating the energy P of the incident wave signal_i；

(4) When the ultrasonic emission signal passes through the interface between the known substance and the unknown substance, the ultrasonic emission signal is reflected back to an ultrasonic reflection signal y (t) through the interface, and the ultrasonic reflection signal returns to the transducer through the known substance;

(5) when detecting the reflected wave reaching the transducer, the transducer starts to receive the reflected wave signal y (t), calculates the energy P of the reflected wave signal_r；

(6) Calculating the acoustic impedance Z of the unknown substance₂And according to acoustic impedance Z₂The substance is identified.

2. The method for rapidly identifying substances based on ultrasonic waves as claimed in claim 1, wherein: the ultrasonic wave emission starting time in the step (2) is t_i1The transmission end time is t_i2I.e. total duration of transmission of T_i：T_i＝t_i2-t_i1。

3. The method for rapidly identifying substances based on ultrasonic waves as claimed in claim 1, wherein: energy P in the step (3)_iThe calculation formula of (2) is as follows:

4. the method for rapidly identifying substances based on ultrasonic waves as claimed in claim 1, wherein: 6. the method for detecting whether the reflected wave reaches the transducer in the step (5) comprises the following steps: when the amplitude of the signal received by the transducer is obviously increased, the reflected wave signal reaches the transducer; the method for judging whether the reflected wave completely reaches the transducer comprises the following steps: when the amplitude of the signal received by the transducer is low, it indicates that the reflected wave signal has completely reached the transducer.

5. The method for rapidly identifying substances based on ultrasonic waves as claimed in claim 1, wherein: in the step (5), the transducer is used to start receiving the reflected wave signal y (t), and the time for starting receiving the reflected wave is t_r1When the reflected wave completely reaches the transducer, the transducer stops receiving the reflected wave for a time t_r2The total duration of the reflected wave received by the transducer is T_r：T_r＝t_r2-t_r1。

6. The ultrasonic-based quick recognition system of claim 1A method of sorting substances, characterized by: energy P in the step (5)_rThe calculation formula is as follows:

7. the method for rapidly identifying substances based on ultrasonic waves as claimed in claim 1, wherein: calculating the acoustic impedance Z of the unknown substance in the step (6)₂The method comprises the following steps: from the value of acoustic impedance Z of a known substance₁Energy P of incident wave signal_iAnd energy P of the reflected wave signal_rCalculating an unknown value of acoustic impedance Z₂The calculation formula is as follows:

from the above formula, the acoustic impedance value Z of the unknown substance can be calculated₂Comprises the following steps:

8. the method for rapidly identifying substances based on ultrasonic waves as claimed in claim 1, wherein: the method for identifying the substance in the step (6) comprises the following steps: because different substances have different acoustic impedance values, the calculated acoustic impedance value Z of the unknown substance₂The specific substance name of the unknown substance can be identified.

Technical Field

The invention relates to the technical field of underwater detection and identification of substances, in particular to a method for quickly identifying substances based on ultrasonic waves.

Background

When underwater, it is often necessary to distinguish between substances of different densities, which have different acoustic impedances. The traditional acoustic impedance measuring method utilizes the definition of acoustic impedance, namely the acoustic impedance is equal to the product of the density of a medium and the sound velocity in the medium in terms of value, so when the acoustic impedance of a certain medium is measured by the traditional method, the density and the sound velocity of the medium need to be respectively measured, and then multiplication is carried out to obtain the acoustic impedance value of the medium, but under some special conditions, the density or the sound velocity of the medium cannot be measured, and the traditional method is not applicable any more.

In response to this problem, the acoustic impedance of an unknown substance is calculated based on the theory of reflection and transmission of ultrasonic waves on an interface formed by media with different acoustic impedances, with the acoustic impedance of a substance known.

1. Ultrasonic wave

Ultrasonic waves are mechanical waves, which are the propagation of mechanical vibrations in a medium, and the frequency is very high, above 20kHz, and cannot be heard by the human ear. The ultrasonic wave has the following propagation characteristics.

1) The directivity is good. The frequency of the ultrasonic wave is very high, the wavelength is equal to the wave speed divided by the frequency, namely the wavelength of the ultrasonic wave is very short, so that the ultrasonic wave can be linearly transmitted like a light wave and shows very good directivity.

2) The power is large. The propagation process of ultrasonic wave is also the propagation process of energy, and according to the physical fluctuation theory, the power of ultrasonic wave refers to the energy transferred in unit time, and is proportional to the square of frequency. Ultrasonic waves are also powerful due to their high frequency, i.e., they deliver a large amount of energy per unit of time.

3) The penetration ability is strong. The intensity attenuation degree of the ultrasonic wave in the propagation process is in negative correlation with the acoustic impedance Z of the medium.

4) The reflection is significant. When the geometric dimensions of an object encountered during wave propagation are several times larger than the wavelength, the wave undergoes significant reflections at the surface of the object. Due to the short wavelength of the ultrasonic waves, the ultrasonic waves can be reflected remarkably when meeting small objects in the process of propagation.

2. Acoustic impedance

The acoustic impedance Z is defined as the ratio of the sound pressure p to the particle velocity v at that location in the sound field, i.e.:

it reflects the damping characteristics of particle vibration caused by acoustic disturbance at a certain position in the medium and influences the sound field characteristics in the medium. The intensity attenuation degree of the ultrasonic wave in the propagation process is in negative correlation with the acoustic impedance Z of the medium, wherein Z is an important physical quantity for describing the mechanical characteristics of the acoustic wave propagation medium, and the magnitude of Z is equal to the density rho of the medium multiplied by the propagation speed c of the acoustic wave, namely Z equals to rho c.

Disclosure of Invention

The invention aims to solve the technical problem that a method for quickly identifying a substance based on ultrasonic waves is provided to solve the problem that the substance cannot be quickly identified under the condition that the density or the sound velocity of the substance cannot be measured in the prior art.

In order to solve the technical problems, the technical scheme of the invention is as follows: a method for rapidly identifying substances based on ultrasonic waves is characterized in that: the method specifically comprises the following steps:

(1) selecting a known substance and an unknown substance, and placing the known substance and the unknown substance together, wherein the acoustic impedance value of the known substance is expressed as Z₁The value of the acoustic impedance of the unknown substance to be resolved is expressed as Z₂；

(2) Vertically transmitting an ultrasonic signal x (t) from a known substance to an unknown substance using a transducer;

(3) calculating the energy P of the incident wave signal_i；

(4) When the ultrasonic emission signal passes through the interface between the known substance and the unknown substance, the ultrasonic emission signal is reflected back to an ultrasonic reflection signal y (t) through the interface, and the ultrasonic reflection signal returns to the transducer through the known substance;

(5) when detecting the reflected wave reaching the transducer, the transducer starts to receive the reflected wave signal y (t), calculates the energy P of the reflected wave signal_r；

(6) Calculating the acoustic impedance Z of the unknown substance₂And according to acoustic impedance Z₂The substance is identified.

Further, in the step (2)Ultrasonic wave emission start time is t_i1The transmission end time is t_i2I.e. total duration of transmission of T_i：T_i＝t_i2-t_i1。

Further, the energy P in the step (3)_iThe calculation formula of (2) is as follows:

further, the method for detecting whether the reflected wave reaches the transducer in the step (5) comprises: when the amplitude of the signal received by the transducer is obviously increased, the reflected wave signal reaches the transducer; the method for judging whether the reflected wave completely reaches the transducer comprises the following steps: when the amplitude of the signal received by the transducer is low, it indicates that the reflected wave signal has completely reached the transducer.

Further, in the step (5), the transducer is used to start receiving the reflected wave signal y (t), and the time for starting receiving the reflected wave is t_r1When the reflected wave completely reaches the transducer, the transducer stops receiving the reflected wave for a time t_r2The total duration of the reflected wave received by the transducer is T_r：T_r＝t_r2-t_r1。

Further, the energy P in the step (5)_rThe calculation formula is as follows:

further, calculating the acoustic impedance Z of the unknown substance in the step (6)₂The method comprises the following steps: from the value of acoustic impedance Z of a known substance₁Energy P of incident wave signal_iAnd energy P of the reflected wave signal_rCalculating an unknown value of acoustic impedance Z₂The calculation formula is as follows:

from the above formula, the acoustic impedance value Z of the unknown substance can be calculated₂Comprises the following steps:

further, the method for identifying the substance in the step (6) is as follows: because different substances have different acoustic impedance values, the calculated acoustic impedance value Z of the unknown substance₂The specific substance name of the unknown substance can be identified.

Compared with the prior art, the invention has the following beneficial effects:

the method for quickly identifying the substance based on the ultrasonic waves utilizes the good directivity, the strong penetrating power and the reflection principle of the ultrasonic waves, reflects the ultrasonic waves on the surface of the unknown substance by transmitting the ultrasonic waves, measures the acoustic impedance of the unknown substance by measuring the energy of incident waves and reflected waves, and indirectly identifies the substance through the acoustic impedance value, thereby avoiding the problem that the substance cannot be identified due to the fact that the acoustic velocity or the density cannot be measured in underwater detection.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments are briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic flow chart of a method for rapidly identifying a substance based on ultrasonic waves according to the present invention.

Fig. 2 is a schematic diagram of a method for rapidly identifying a substance based on ultrasonic waves according to the present invention.

Detailed Description

The technical solution of the present invention will be clearly and completely described by the following detailed description.

The invention provides a method for quickly identifying a substance based on ultrasonic waves, which specifically comprises the following steps as shown in figure 1:

(1) selecting a known substance, wherein the acoustic impedance value table of the known substanceShown as Z₁The value of the acoustic impedance of the unknown substance to be resolved is expressed as Z₂；

(2) Placing a known substance and an unknown substance together, and vertically transmitting an ultrasonic signal x (t) from the known substance to the unknown substance by using a transducer as shown in FIG. 2, wherein the ultrasonic transmission starts at a time t_i1The transmission end time is t_i2I.e. total duration of transmission of T_i：T_i＝t_i2-t_i1Calculating the energy P of the incident wave signal_iThe calculation formula is as follows:

(3) when the ultrasonic emission signal passes through the interface between the known substance and the unknown substance, the ultrasonic emission signal is reflected by the interface to return an ultrasonic reflection signal y (t), the ultrasonic reflection signal returns to the transducer through the known substance, and when the amplitude of the signal received by the transducer is obviously increased, the reflected wave signal reaches the transducer;

(4) when the reflected wave is detected to reach the transducer, the transducer starts to receive the reflected wave signal y (t), and the time for starting to receive the reflected wave is t_r1When the amplitude of the signal received by the transducer is low, it indicates that the reflected wave signal has completely reached the transducer, and the reception of the reflected wave by the transducer is stopped for a time t_r2The total duration of the reflected wave received by the transducer is T_r：T_r＝t_r2-t_r1Calculating the energy P of the reflected wave signal_rThe calculation formula is as follows:

(5) from the value of acoustic impedance Z of a known substance₁Energy P of incident wave signal_iAnd energy P of the reflected wave signal_rCalculating an unknown value of acoustic impedance Z₂The calculation formula is as follows:

from the above formula, the acoustic impedance value Z of the unknown substance can be calculated₂Comprises the following steps:

(6) because different substances have different acoustic impedance values, the acoustic impedance value Z of the unknown substance calculated according to the step (5)₂The specific substance name of the unknown substance can be identified.

The above-mentioned embodiments are merely descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention, and various modifications and improvements made to the technical solutions of the present invention by those skilled in the art should fall into the protection scope of the present invention without departing from the design concept of the present invention, and the technical contents of the present invention as claimed are all described in the technical claims.