CN113325086A - Detection system based on electromagnet type electromagnetic acoustic transducer - Google Patents
Detection system based on electromagnet type electromagnetic acoustic transducer Download PDFInfo
- Publication number
- CN113325086A CN113325086A CN202110557909.7A CN202110557909A CN113325086A CN 113325086 A CN113325086 A CN 113325086A CN 202110557909 A CN202110557909 A CN 202110557909A CN 113325086 A CN113325086 A CN 113325086A
- Authority
- CN
- China
- Prior art keywords
- circuit
- signal
- output
- excitation
- electromagnet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 32
- 230000005284 excitation Effects 0.000 claims abstract description 77
- 230000003321 amplification Effects 0.000 claims abstract description 42
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 42
- 230000005291 magnetic effect Effects 0.000 claims abstract description 39
- 238000013461 design Methods 0.000 claims abstract description 36
- 238000000034 method Methods 0.000 claims abstract description 7
- BLRBOMBBUUGKFU-SREVYHEPSA-N (z)-4-[[4-(4-chlorophenyl)-5-(2-methoxy-2-oxoethyl)-1,3-thiazol-2-yl]amino]-4-oxobut-2-enoic acid Chemical compound S1C(NC(=O)\C=C/C(O)=O)=NC(C=2C=CC(Cl)=CC=2)=C1CC(=O)OC BLRBOMBBUUGKFU-SREVYHEPSA-N 0.000 claims abstract 12
- 238000005070 sampling Methods 0.000 claims description 22
- 230000005669 field effect Effects 0.000 claims description 18
- 239000000872 buffer Substances 0.000 claims description 9
- 238000006243 chemical reaction Methods 0.000 claims description 6
- 230000000670 limiting effect Effects 0.000 claims description 6
- 239000003990 capacitor Substances 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 238000002955 isolation Methods 0.000 claims description 3
- 230000036961 partial effect Effects 0.000 claims description 3
- 230000003139 buffering effect Effects 0.000 claims description 2
- 238000007599 discharging Methods 0.000 claims description 2
- 238000005516 engineering process Methods 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 claims 1
- 238000003786 synthesis reaction Methods 0.000 claims 1
- 238000012360 testing method Methods 0.000 abstract description 25
- 238000002474 experimental method Methods 0.000 abstract description 6
- 238000012795 verification Methods 0.000 abstract description 2
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 230000002829 reductive effect Effects 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 238000012544 monitoring process Methods 0.000 description 3
- 239000000523 sample Substances 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000003302 ferromagnetic material Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000009659 non-destructive testing Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000002604 ultrasonography Methods 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- MUBKMWFYVHYZAI-UHFFFAOYSA-N [Al].[Cu].[Zn] Chemical compound [Al].[Cu].[Zn] MUBKMWFYVHYZAI-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000008186 active pharmaceutical agent Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 239000011449 brick Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000000875 corresponding effect Effects 0.000 description 1
- 239000007822 coupling agent Substances 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000005294 ferromagnetic effect Effects 0.000 description 1
- 238000002595 magnetic resonance imaging Methods 0.000 description 1
- 230000005389 magnetism Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000005298 paramagnetic effect Effects 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/30—Arrangements for calibrating or comparing, e.g. with standard objects
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Ultra Sonic Daignosis Equipment (AREA)
Abstract
The invention discloses a detection system based on an electromagnet type electromagnetic acoustic transducer, which is applied to a detection experiment of the electromagnet type electromagnetic acoustic transducer. The system comprises a double-channel arbitrary signal excitation circuit, a high-power high-noise-ratio amplification circuit and a double-channel signal high-gain acquisition circuit, and realizes excitation of the electromagnet type electromagnetic acoustic sensor and reception of ultrasonic signals and magnetic signals. The design can generate any waveform, the frequency, the period, the amplitude, the repetition frequency and the like of an output signal can be regulated through a program, the amplified output of an EMAT excitation signal is realized through a power amplification circuit, the highest output instantaneous current can reach 32A, and the voltage can reach 800 Vpp. The method is characterized in that a two-stage program-controlled amplified high-gain signal acquisition circuit is adopted to realize acquisition of millivolt-level ultrasonic signals, and an acquisition circuit with an attenuation circuit is designed to acquire magnetic signals. The feasibility of the system is proved through excitation circuit testing, power amplifier circuit testing and system experiment verification.
Description
Technical Field
The invention relates to a detection system based on an electromagnet type electromagnetic acoustic transducer, which comprises a double-channel arbitrary signal excitation circuit, a high-power high-noise-ratio amplification circuit and a double-channel signal acquisition circuit. The device can be applied to detection experiments of the electromagnet type electromagnetic acoustic transducer, and can realize excitation of the electromagnet type electromagnetic acoustic transducer and reception of ultrasonic signals and magnetic signals.
Background
Ultrasonic guided waves have been widely used as a nondestructive evaluation tool because of their advantages that guided waves are highly sensitive to disturbance in propagation and can propagate over a long distance even in materials with high attenuation rates, as a means for nondestructive testing. There are many ways to excite guided waves, such as laser excitation, piezoelectric excitation, and excitation using electromagnetic acoustic transducers. An Electromagnetic Acoustic Transducer (EMAT) has the advantages of simple structure, no need of coupling and the like, and has great application value in the field of ultrasonic nondestructive testing. The EMAT has the working principle that: an EMAT coil which is introduced with high-frequency alternating current can induce eddy current in a test piece (mainly near the skin depth), and the eddy current enables surrounding particles to generate elastic deformation and periodic vibration under the action of a magnetic field to excite electromagnetic ultrasonic waves; the position and size of the defect can be determined by receiving reflected waves or transmitted waves generated when the defect is encountered in the ultrasonic wave propagation process. The main advantages of EMATs compared to piezoelectric ultrasound are as follows:
(1) the EMAT does not need to coat a coupling agent on the surface of the test piece during detection, can carry out non-contact on-line detection, can directly contact the surface of the test piece, and has low requirements on the test piece and the detection environment, so that the adaptability of the EMAT to different detection test pieces and detection environments is enhanced;
(2) the ultrasonic wave of the EMAT comes from the skin depth layer of the test piece, so the roughness and smoothness of the surface of the test piece have small influence on the detection result. During detection, the test piece does not need to be pretreated, so that the detection efficiency is improved;
(3) the EMAT has the advantages of relatively simple structure, strong designability and simple operation. The magnetic resonance imaging device mainly comprises a magnet and a coil, and can excite various forms and various modes of guided waves by changing the structures of the magnet and the coil.
EMATs are widely studied because of the above-mentioned advantages. A conventional EMAT consists of three parts: a coil (including a transmitting coil and a receiving coil), a magnet for providing a bias magnetic field and a sample to be detected. According to different properties of test pieces, the EMAT working mechanism can be divided into three forms of Lorentz force, magnetostriction force and magnetic force. For non-ferromagnetic materials (e.g., aluminum, copper, zinc, etc.), the lorentz force is the primary cause of ultrasonic waves; in ferromagnetic materials (such as iron, cobalt, nickel, etc.), magnetostrictive force, magnetic force, and lorentz force act together on a test piece to generate and receive ultrasonic waves. The conventional EMAT mainly uses a permanent magnet to provide a static magnetic field, but the EMAT based on the permanent magnet design has the following disadvantages:
(1) the permanent magnet magnetic field exists and cannot be changed at any time, the adsorption force is strong when the permanent magnet magnetic field is detected on a ferromagnetic test piece, the movement is difficult, and the coil and the magnet are easy to wear;
(2) the iron scraps around the iron-clad brick are easy to adsorb and difficult to clean when placed;
(3) and cannot work at high temperature. Because the permanent magnet has a Curie point, when the working environment is high (about 1/3 Curie temperature), the permanent magnet gradually becomes paramagnetic, and the magnetism is greatly reduced.
Therefore, in view of the disadvantages of the permanent magnet EMAT, researchers have proposed and studied replacement of permanent magnets with electromagnets. However, no complete system can be used for experimental research on the electromagnet EMAT, and related research on the electromagnet EMAT, and currently, a detection system for the electromagnet EMAT is rarely reported.
Disclosure of Invention
The invention aims to design a detection system based on an electromagnet type electromagnetic acoustic transducer, which can realize the excitation and the receiving of an electromagnet type EMAT signal. The system mainly comprises a double-channel excitation circuit of an EMAT excitation signal and an electromagnet excitation signal, an EMAT power amplification circuit, an electromagnet excitation power amplification circuit and an AD sampling circuit. The design of the dual-channel excitation signal source takes a DDS (direct digital synthesizer) based on an FPGA (field programmable gate array) as a core, and can generate any type of signals, wherein the signal frequency range is 0-5 MHz, and the output voltage amplitude range is 0-5V. The AD sampling circuit consists of two paths, wherein one path takes an ADC12040 chip as a core and is used for receiving ultrasonic signals, and the two-stage program control amplification of an AD8367 chip is matched, so that the maximum echo gain can reach 80dB, the maximum sampling frequency is 40MHz, and the resolution is 12 bit; the other path of sampling circuit takes an AD9226 chip as a core, the maximum sampling rate is 65MHz, and the maximum sampling rate is used for monitoring the magnetic field intensity of the electromagnet in real time. The system adopts FPGA as the main control and an EP4CE15F17C8 chip of Altera company as the core to carry out logic control.
In order to achieve the purpose, the invention adopts the following design scheme:
a detection system based on an electromagnet type electromagnetic acoustic transducer mainly comprises a two-channel arbitrary signal excitation circuit, an EMAT power amplification circuit, an electromagnet power amplification circuit and a two-channel acquisition circuit. The EMAT power amplifying circuit is a circuit with high frequency, large current, large voltage and high signal-to-noise ratio. The cut-off frequency of the EMAT high-frequency power amplifying circuit can reach 10MHz, the maximum output voltage can reach 800Vpp, and the maximum output instantaneous current can reach 32A. The output of the two-channel arbitrary signal excitation circuit is two paths of analog signals, one path of signal EAMT excites the signal, the output port is connected with the EMAT power amplification circuit to realize the amplification of current and voltage, and the signal is connected with the EMAT excitation coil after passing through the EMAT power amplification circuit. The other path of output signal of the double-channel arbitrary signal excitation circuit is an electromagnet excitation signal, and the signal is amplified and then output to an electromagnet excitation coil for excitation through an output port and an electromagnet power amplification circuit. The two-channel acquisition circuit is two-channel signal acquisition circuit of ultrasonic signal and magnetic signal, and EMAT receiving coil is connected with ultrasonic signal acquisition port in acquisition circuit, and another interface is the magnetic signal delivery outlet, links to each other with hall sensor.
The double-channel arbitrary signal excitation circuit can generate arbitrary waveforms by adopting a scheme based on the combination of FPGA and DDS technologies. The system mainly comprises an FPGA main control chip, a high-speed digital-to-analog converter, a software control amplitude modulation module, a single-end to differential circuit, a 7-order Butterworth low-pass filter and a hardware control amplitude modulation module. The FPGA main control chip is connected with the high-speed digital-to-analog converter, converts a digital signal into an analog signal, then connects the output end of the high-speed digital-to-analog converter with the single-ended to differential circuit, converts the differential signal into a single-ended signal, and then the single-ended to differential circuit is connected with the 7-order Butterworth low-pass filter and the hardware control amplitude modulation module to realize signal output. Firstly, an arbitrary signal generator is built in an FPGA main control chip, data are transmitted to a high-speed DAC chip through an 8-bit parallel interface, a DAC converts digital signals into analog signals, digital offset and gain adjustment are carried out through a DAC chip TLC5615 to achieve partial amplitude adjustment of software, differential signals are converted into single-ended signals through AD8065, and then a 7-order Butterworth filter is adopted to carry out low-pass filtering and then is connected into an operational amplifier to achieve hardware amplitude modulation. The dual-channel excitation circuit adopts the same design scheme, can generate any waveform by design, and the frequency, the period, the amplitude, the repetition frequency and the like of an output signal can be adjusted by a program.
The EMAT power amplification circuit has the main function of amplifying a low-power signal generated by the excitation circuit so as to effectively excite the transducer to generate ultrasonic guided waves. The most effective method for improving the output voltage is to adopt a broadband transformer to carry out boost conversion at an output stage, the circuit is composed of a power supply circuit, a driving circuit and a power output circuit, the driving circuit is directly connected with the power output circuit, and the power supply circuit provides required voltage for the driving circuit and the power output circuit. The power output circuit is the main energy conversion part of the circuit and comprises a field effect transistor amplifying circuit, a switch control circuit, an output transformer and the like. The field effect transistor amplifying circuit is directly connected with the switch control circuit, and the output end of the switch control circuit is connected with the output transformer.
The electromagnet power amplifying circuit realizes the excitation of the electromagnet and provides a magnetic field for exciting the ultrasonic signal by the EMAT. The circuit needs to provide a sufficiently large current to cause the electromagnet to generate a sufficiently large magnetic field to ensure that the EMAT is able to excite the ultrasonic signal. In addition, in order to verify the influence of different excitation signals on the performance of the EMAT, an electromagnet excitation amplifying circuit needs to be designed to amplify different types of signals.
The two-channel signal acquisition circuit is used for acquiring ultrasonic signals received by the EMAT and magnetic field signals of the electromagnet in the system respectively. The circuit design is carried out according to the characteristics of two paths of signals, the amplitude of the ultrasonic signal is small and is a millivolt level signal, so that multi-level pre-amplification needs to be designed to ensure that the signal can be collected by a sampling chip; the magnetic field signal is used for monitoring the intensity of a magnetic field in real time, a Hall element is used for collecting the magnetic signal, the signal amplitude is large, and in order to calculate the maximum magnetic field intensity, the requirements of large sampling rate and high reduction of the signal amplitude are met.
The existing detection system of the electromagnet EMAT is formed by combining a plurality of devices, the experimental system is bulky, an electromagnet excitation source and an EMAT excitation source are separated, a function generator is adopted to excite the electromagnet, power amplification is carried out through a power amplifier, and RPR 4000 is adopted to excite and acquire signals of the EMAT; and joint modulation of the electromagnet excitation signal and the EMAT excitation signal cannot be realized. The invention discloses an electromagnet EMAT excitation/receiving integrated system, which realizes the comprehensive detection of the electromagnet EMAT, and simultaneously acquires ultrasonic signals and electromagnetic signals to realize the simultaneous detection of the magnetic signals and the acoustic signals. The two-channel excitation circuit board can realize excitation of any signal, and can study the influence of the type and amplitude of an electromagnet excitation signal and the delay time between the electromagnet excitation signal and an EMAT excitation signal on a signal generated by the EMAT. The EMAT power amplification circuit can meet the excitation of an electromagnetic acoustic transducer in the frequency range of 10MHz, the designed double-channel acquisition circuit can acquire millivolt ultrasonic signals through the two-stage program control amplification circuit, and the direct coupling relation between the magnetic signals and the ultrasonic signals can be explored through joint modulation of the ultrasonic signals and the magnetic signals.
Drawings
FIG. 1 is a block diagram of a detection system for an electro-magnet type electro-magnetic acoustic transducer;
FIG. 2 is a block diagram of a dual channel excitation circuit design;
FIG. 3 AD9708 circuit layout;
FIG. 4 TLC5615 circuit design;
FIG. 57 is a schematic circuit diagram of an order Butterworth low pass filter;
FIG. 6 is a block diagram of an EMAT power amplifier circuit design;
FIG. 7 THS4151 differential amplifier circuit layout;
FIG. 8 reference voltage amplifying circuit
FIG. 9a) BUF634 signal buffer circuit design, b) IRF510 drive circuit design;
FIG. 10 shows a transformer amplifier circuit layout;
FIG. 11 shows a design of an excitation amplifying circuit of an electromagnet;
FIG. 12 is a block diagram of an AD sampling circuit design;
fig. 13 ADC12040 sampling circuit layout;
FIG. 14A/D8367 shows an enlarged circuit layout;
FIG. 15 MAX5102 programmable circuit layout;
fig. 16 AD9226 sampling circuit layout;
FIG. 17 is an excitation circuit board test signal;
FIG. 18 EMAT power amplifier circuit board signal testing;
figure 19 the transducer acquires the resulting ultrasound signals.
Detailed Description
The invention is further illustrated by the following figures and examples.
A detection system based on an electromagnet type electromagnetic acoustic transducer is provided with a double-channel arbitrary signal excitation circuit, and two paths of arbitrary signals with adjustable waveforms, frequencies, periods and amplitudes can be generated by utilizing the circuit. One path of output provides an excitation signal for the EMAT, and the other path is the excitation signal of the electromagnet coil. An EMAT power amplification circuit with high frequency band, large current and high signal-to-noise ratio is designed, the maximum output instantaneous current can reach 32A, and the output voltage can reach 800 Vpp. An electromagnet excitation power amplifier circuit providing enough current is designed, so that the electromagnet generates a magnetic field with enough magnitude, and the EMAT can be ensured to excite an ultrasonic signal. A double-channel signal acquisition circuit with high gain and high noise-to-noise ratio is designed to realize acquisition of ultrasonic signals and magnetic signals. A USB data communication circuit is designed, and CH376 is used as a main unit and used for data transmission between an upper computer and hardware.
The detection system of the electromagnet type electromagnetic acoustic transducer is shown in a block diagram in fig. 1, wherein waveform data is generated by an FPGA, converted into an analog signal through a digital-to-analog converter in an excitation circuit, filtered by a filter in the excitation circuit, and subjected to amplitude adjustment and output through an amplifier. The two paths of generated signals are amplified and output to the transducer and the magnet exciting coil of the electromagnet through the EMAT power amplifying circuit and the electromagnet power amplifying circuit respectively. And the signal acquisition part transmits acquired data to the FPGA through a double-channel acquisition circuit by using the ultrasonic signal and the magnetic signal acquired by the transducer and the Hall element, and the FPGA transmits the acquired data to the host computer for display through the USB communication circuit.
The design block diagram of the dual-channel excitation circuit is shown in fig. 2, which shows the design scheme of one channel of signals, and the design scheme of the other channel is completely the same. Firstly, an arbitrary signal generator is built in an FPGA (field programmable gate array), data are transmitted to a high-speed DAC (digital-to-analog converter) chip through an 8-bit parallel interface, the DAC converts a digital signal into an analog signal, digital offset and gain adjustment are carried out by adopting a DAC chip TLC5615 to realize partial amplitude adjustment of software, a differential signal is converted into a single-ended signal through AD8065, and then a 7-order Butterworth filter is adopted to carry out low-pass filtering and then is connected into an operational amplifier to realize hardware amplitude modulation. The circuit design of the AD9708 is shown in FIG. 3, wherein 8 parallel interfaces realize the transmission of digital signals with the FPGA through 8 data lines, and a clock is constructed by the PLL inside the FPGA and then is input through a clock I/O port. Where the 16 pin REFLO is the reference voltage ground when an internal 1.2V reference voltage source is used. The internal reference is disabled when connected to the AVDD. Pin 17 REFIO is a reference input/output pin. When the internal reference is disabled, i.e., REFLO is connected to AVDD, it is used as a reference input. When an internal reference voltage is employed, i.e., REFLO is connected to the ACOM port, it is used as an output for a 1.2V reference voltage. When the internal reference voltage source is activated, a 0.1 muF capacitor is required to be connected to the ACOM port. In the design, a RELFLO pin is connected to AVDD, an internal reference power supply is disabled, and an external reference power supply is introduced to realize the control of the amplitude of the output voltage of the AD9708 through software. The specific method is that the output of the DAC chip TLC5615 is connected to a 16-pin REFIO of the AD9708 to be used as an external reference voltage, and the TLC5615 is controlled and output by an FPGA internal program to perform digital offset and gain adjustment. TLC5615 is a serial digital-to-analog converter, can complete serial input of 10-bit data only through 3 serial buses, and is easy to connect with an industry standard microprocessor. In addition, a precision programmable reference TL431 is used in the circuit of TLC5615 to stabilize the output voltage. When the input voltage is increased, the output voltage is increased to increase the output sampling, at this time, the current of the TLC431 internal circuit is increased by adjusting the current of the TLC431 internal circuit, so that the current of the internal current limiting resistor is increased, the current is increased to increase the voltage drop of the current limiting resistor, and the output voltage is equal to the input voltage and the voltage division of the current limiting resistor, so that the output voltage value is reduced, and the voltage stabilization is realized. The circuit layout of TLC5615 is shown in fig. 4. The analog signal which is constructed and output by the DDS usually has high-frequency noise, and a low-pass filter circuit is required to be introduced in order to smooth the output signal of the DAC and restrain noise interference. The filter circuit design is shown in fig. 5, the filter is a passive low pass filter, a 7-order butterworth filter is adopted, the 3dB bandwidth is 30MHz, and when the cut-off frequency is 80MHz, the attenuation is 47.5 dB.
The design block diagram of the EMAT power amplification circuit is shown in FIG. 6, an EMAT excitation signal is differentiated and amplified through a differential chip, a bias signal is provided for the differential chip through an I/O port of an FPGA, a starting voltage is provided for a rear-end field effect transistor, then data is buffered through a buffer, output current is increased, synchronous transmission of two paths of data is achieved, and the functions of coordination and buffering are achieved. Because the output current of the buffer is small, the maximum output is 250mA, the output current needs to be increased to drive the rear-stage field effect transistor to work, the output current is increased by adopting the driving tube, and then the signal amplification is realized by the field effect transistor and the transformer. The THS4151 differential amplifier circuit is shown in FIG. 7, where VocmThe reference voltage of the THS4151 circuit is input, namely, the direct current bias is added into the input signal, so that sufficient starting voltage is provided for a subsequent field effect transistor amplifying circuit, and the field effect transistor is ensured to work in an amplifying area. The output of the I/O of the FPGA is adopted as V in the designocmThe signal source can simultaneously generate the excitation signal and the bias signal of the dual-channel excitation plate through program control, so that the field effect tube only needs to work when the excitation signal is output, the field effect tube can be effectively prevented from being always in an amplification area, the power dissipation is reduced, and the field effect tube is prevented from being burnt out due to overheating. The I/O output voltage of the actual FPGA is only 3.3V and is not enoughAnd the subsequent field effect transistors are all ensured to be conducted, so that a reference voltage amplifying circuit is introduced, as shown in fig. 8. And amplifying the 3.3V voltage generated by the FPGA by using an operational amplifier AD8065 and then outputting the amplified voltage. In order to ensure the synchronization of the two signals generated after the signal differentiation, buffers are added at the rear ends of the two differential signals respectively, and the selected device is BUF 634. BUF634 is a high-speed gain open-loop buffer that can be used inside the feedback loop of an operational amplifier to increase output current, eliminate thermal feedback, and improve capacitive load drive. Differential signal passes through the BUF634 buffer back rethread field effect transistor respectively and enlargies, but MOS pipe need consider the capacitive reactance problem that parasitic capacitance brought when passing through alternating signal, consequently not only will guarantee that MOS pipe input signal is greater than opening voltage, will guarantee moreover that input current is enough big, so join IRF510 drive circuit at MOS pipe amplifier circuit anterior segment, improve output current to guarantee that MOS pipe can normally work. The BUF634 signal buffer circuit and the IRF510 driving circuit are shown in FIG. 9. Finally, the transformer amplification circuit realizes the amplification of the output signal voltage, the schematic design of the circuit is shown in fig. 10, and two transformer structures are adopted for multi-stage amplification. The main transformer adopts a center tap connection method, the turn ratio of a transformer coil is 1:1:4, a center connector is connected to a 200V direct-current power supply, two ends of a primary coil of the transformer are respectively connected to the same-direction output end and the reverse-direction output end of a differential signal, and the differential signal is converted into a single-end signal to be output through a secondary coil of the transformer after being respectively amplified. Therefore, the amplification factor of the transformer can be calculated to be 4 times when 1V is introducedPPThe output of the signal can reach 800VPPHowever, the corresponding current limit value is reduced to 1/4, and the structure of the parallel field effect tube is adopted in the design circuit to increase the limit value of the current in the signal output to the transducer in consideration of the large current condition of the EMAT.
The electromagnet power amplifying circuit is designed as shown in fig. 11. 36 high-capacity capacitors are used for charging and discharging, so that the output signal reaches the maximum value instantly. The design uses N-channel enhancement mode fet IRFZ44N as the output switch and TC4428 as the driver for the MOSFET transistor, which can easily switch 1000pF gate capacitance in 30ns and provide low enough impedance in both ON and OFF states to ensure that the desired state of the MOSFET is not affected even by large transients. The LT3028 in the circuit acts as a low dropout linear regulator providing a 12V power supply for the TC 4428. Since the maximum continuous DS current of one piece of IRFZ44N at 24V is only 6A, 10 pieces of IRFZ44N are connected in parallel to increase the output current of the excitation circuit in order to increase the maximum operating current of the electromagnet. The drains of 10 pieces of IRFZ44N are all connected with the grid, and the sources are connected with 0.1 omega resistor in series, so that the effect of current equalization is achieved, and the MOSFET can be prevented from being burnt due to uneven internal resistance. Since the total gate capacitance exceeds 10nF after the multiple groups of MOSFETs are connected in parallel, in order to ensure the response speed of the driving current of the electromagnet and the stability of the driving voltage, the buffer OPA2156 is used as a MOSFET gate driver, and the chip can provide the driving current of 100mA at the maximum and can meet the driving requirements of the MOSFETs. As can be seen from the data sheet of IRFZ44N, the turn-off voltage of the MOSFET is not greater than 4V, and the turn-on voltage is not less than 4.5V, so that in order to control the output current of the driving circuit in a linear manner, the gate voltage of the MOSFET needs to be precisely controlled to operate in a linear operating region. In a voltage interval between the cut-off voltage and the starting voltage, the source electrode current variation and the grid electrode voltage variation can be approximately considered to be positively correlated, and accurate output current control can be realized through calibration and calibration of an upper computer.
The two-channel acquisition circuit is used for acquiring ultrasonic signals received by the EMAT and magnetic field signals of the electromagnet respectively. The circuit design is carried out according to the characteristics of two paths of signals, the amplitude of the ultrasonic signal is small and is a millivolt level signal, so that multi-level pre-amplification needs to be designed to ensure that the signal can be collected by a sampling chip; the magnetic field signal is used for monitoring the intensity of a magnetic field in real time, a Hall element is used for collecting the magnetic signal, the amplitude of the signal is large, and the signal can not be amplified by a preceding stage. The design block diagram of the ultrasonic signal acquisition circuit is shown in fig. 12, and the circuit adopts two-stage program control amplification, so that 80dB amplification can be realized to the maximum. In order to avoid the influence of the high-voltage signal of the crosstalk on the sampling chip and protect the rear-stage circuit, an isolation amplitude limiting circuit is added at the signal output end to clamp the voltage, and a high-pass RC filter is used for removing direct-current components. The sampling circuit designed by adopting the ADC12040 sampling chip is shown in FIG. 13, the chip is powered by 5V, and the division of digital/analog power supply and ground is performed. The sampling clock is controlled by the FPGA to be output, signals are pre-processed and then converted from single-ended signals to differential signals through the LMH6550MA and serve as the input of the ADC12040, an output enable pin OE and a power-down input pin are connected to the FPGA through an I/O port, and the start and stop of program control sampling are achieved. The program-controlled amplifying circuit consists of a preposed isolating/amplitude limiting circuit, an OPA340NA impedance matching circuit, a gain control circuit and an AD8367 amplifying circuit. The isolation/limiter circuit clamps the voltage by using the nonlinear characteristic and the switching characteristic of the diode, and can isolate the interference beyond +/-0.7V. Since the OPA340NA has a good low output impedance and high input impedance characteristic, impedance matching of the front-end circuit can be achieved. Two-stage AD8367 amplifier circuit as shown in fig. 14, AD8367 is a high performance variable gain amplifier with linear dB gain control, suitable for low frequency khz to hundreds of mhz frequency range. The gain range of the AD8367 is-2.5 dB-45 dB, and the-3 dB bandwidth can reach 500 MHz. The program control circuit is designed by adopting an 8-bit DAC chip MAX5102 as shown in FIG. 15, wherein the MAX5102 has ultra-low power consumption, and the current is only 0.2mA during operation. The FPGA outputs 8-bit parallel data to realize output voltage control, and when a pin WR signal is pulled high, MAX5102 realizes digital quantity conversion into voltage output. The magnetic signal AD acquisition circuit is designed by adopting an AD9226 chip, the AD9226 is a 12-bit AD conversion chip, single power supply is adopted for power supply, and an on-chip high-performance sample-hold amplifier and a reference voltage source are arranged in the AD9226 chip. By adopting a multi-stage differential pipeline architecture, the data rate can reach 65MSPS, and no code loss is ensured in the whole working temperature range. With high speed, low cost CMOS processes and novel architectures, resolution and speed can reach the level of existing bipolar schemes, while power consumption costs are much lower. As shown in fig. 16, the AD9226 sampling circuit configures the AD9226 as a single-ended input mode, and the circuit uses an AD chip internal reference source, and uses a VREF pin as a reference voltage output port, and can provide two reference voltages of 1V and 2V. The selection is carried out through a SENSE pin, and when the SENSE pin is connected with GND, the reference voltage is 2V; when SENSE is connected to VREF, the reference voltage is 1V. In this design, the reference voltage is chosen to be 2V, so the SENSE pin is connected to GND. In addition, in order to expand the sampling voltage range, an attenuation circuit is designed in the circuit by using a reference voltage of 2V. The attenuation circuit has the function of reducing the input voltage according to a certain proportion to enable the input voltage to meet the input range of the AD input end (the voltage range of the AD9226 input end is 1-3V). The design needs to satisfy an input range of 0 to +5V, where the design input range is-5V to +5V, thus reducing the voltage from-5V to +5V to a range of 1V to 3V.
1) Stimulus circuit testing
And connecting the dual-channel excitation circuit board to an I/O port of the FPGA core board, and downloading a program through a JTAG connecting line to test the performance of the excitation circuit board. And a channel 1 of the double-channel excitation plate outputs a sine signal modulated by a five-period Hanning window through FPGA program control as an EMAT excitation signal, and a channel 2 outputs a sine signal as an electromagnet excitation signal. The output signals are connected to oscilloscope viewing signals and the data is stored, respectively, as shown in fig. 17. Wherein, the graph a) is the experimental result of 1-channel signal output, and b) is the experimental result of 2-channel. As can be seen from the waveform curve in the graph, the output signal is smooth, the signal-to-noise ratio is high, and the signal frequency is mainly concentrated near 5MHz according to the frequency spectrum curve in the graph. The reasonability and the feasibility of the design of the dual-channel excitation circuit are verified through experiments, and the fact that the dual-channel excitation circuit board can obtain the required excitation signal is proved.
2) EMAT power amplifier circuit testing
And (3) building an EMAT power amplification circuit test system, wherein the system is powered by a KORAD power supply, the bias signal and the test signal are provided by a function generator, and the two signals are externally triggered by the function generator to realize signal synchronization. The bias signal is set to be a 250kHz pulse square wave signal, the voltage is set to be 3.3V, the test signal is set to be a 2-cycle sinusoidal signal with the frequency of 1MHz, the output end of the test signal is connected to a 50 omega resistor, and the test signal is observed and stored through an oscilloscope. As shown in fig. 18, the final output signal of the power amplifier circuit board is used, and because the voltage amplitude is high, a probe pen attenuated by 100 times is used to connect the probe pen to two ends of a 50 Ω resistor for signal acquisition. The output signal of the power amplifier is observed, the signal is smooth, the noise is small, the peak value of the measurement peak can reach 1000Vpp, and the EMAT excitation requirement can be met.
3) Test system experimental verification
The output of the double-channel excitation circuit is respectively connected to the EMAT power amplification circuit and the electromagnet power amplification circuit, and then is connected with the transducer and the electromagnet excitation coil, the experiment adopts a self-exciting and self-receiving connection mode, and the signal input port of the ultrasonic signal acquisition circuit is connected with the EMAT power amplification circuit board. The magnetic signal acquisition channel is connected with the Hall sensor through a signal wire, measures the magnetic signal of the electromagnet and calculates to obtain the magnetic field intensity. The computer downloads the control program of the FPGA into the FPGA core board through a JTAG downloader, the acquired signals are shown in figure 19, the thickness of the steel plate adopted in the experiment is 30mm, the wave velocity is 3320m/s, the signals can be calculated through transit time analysis, the first wave packet is the first bottom surface reflection echo, and the second wave packet is the second bottom surface reflection echo. The experimental results obtained from the tests prove that the designed system is feasible.
Claims (10)
1. A detecting system based on an electromagnet type electromagnetic acoustic transducer is characterized in that: the device comprises a double-channel arbitrary signal excitation circuit, an EMAT power amplification circuit, an electromagnet power amplification circuit and a double-channel acquisition circuit; the output of the two-channel arbitrary signal excitation circuit is two paths of analog signals, one path of signal EAMT excites a signal, an output port is connected with the EMAT power amplification circuit to realize the amplification of current and voltage, and the signal is connected with the EMAT excitation coil after passing through the EMAT power amplification circuit; the other path of output signal of the double-channel arbitrary signal excitation circuit is an electromagnet excitation signal, and the signal is amplified and then output to an electromagnet excitation coil for excitation through an output port and an electromagnet power amplification circuit; the two-channel acquisition circuit is two-channel signal acquisition circuit of ultrasonic signal and magnetic signal, and EMAT receiving coil is connected with ultrasonic signal acquisition port in acquisition circuit, and another interface is the magnetic signal delivery outlet, links to each other with hall sensor.
2. The detection system based on the electromagnet type electromagnetic acoustic transducer as claimed in claim 1, wherein: the double-channel arbitrary signal excitation circuit generates an arbitrary waveform by combining FPGA (field programmable gate array) and DDS (direct digital synthesis) based technologies; the system comprises an FPGA main control chip, a high-speed digital-to-analog converter, a software control amplitude modulation module, a single-end to differential circuit, a 7-order Butterworth low-pass filter and a hardware control amplitude modulation module; the FPGA main control chip is connected with the high-speed digital-to-analog converter, converts a digital signal into an analog signal, then connects the output end of the high-speed digital-to-analog converter with the single-ended to differential circuit, converts the differential signal into a single-ended signal, and then the single-ended to differential circuit is connected with the 7-order Butterworth low-pass filter and the hardware control amplitude modulation module to realize signal output; firstly, constructing an arbitrary signal generator in an FPGA main control chip, transmitting data to a high-speed DAC chip through an 8-bit parallel interface, converting a digital signal into an analog signal by the DAC chip, performing digital offset and gain adjustment by adopting a DAC chip TLC5615 to realize partial amplitude adjustment of software, converting a differential signal into a single-ended signal through AD8065, and then performing low-pass filtering by adopting a 7-order Butterworth filter and accessing an operational amplifier to realize hardware amplitude modulation; the double-channel excitation circuit adopts the same design scheme, arbitrary waveforms are designed and generated, and the frequency, the period, the amplitude and the repetition frequency of an output signal are adjusted through a program.
3. The detection system based on the electromagnet type electromagnetic acoustic transducer as claimed in claim 1, wherein: the EMAT power amplifying circuit amplifies the small-power signal generated by the exciting circuit and excites the transducer to generate ultrasonic guided waves; the most effective method for improving the output voltage is to adopt a broadband transformer to carry out boost conversion at an output stage, a power circuit, a driving circuit and a power output circuit form the driving circuit to be directly connected with the power output circuit, and the power circuit provides required voltage for the driving circuit and the power output circuit; the power output circuit is an energy conversion part of the circuit and comprises a field effect transistor amplifying circuit, a switch control circuit and an output transformer; the field effect transistor amplifying circuit is directly connected with the switch control circuit, and the output end of the switch control circuit is connected with the output transformer.
4. The detection system based on the electromagnet type electromagnetic acoustic transducer as claimed in claim 1, wherein: the electromagnet power amplifying circuit realizes the excitation of the electromagnet and provides a magnetic field for exciting an ultrasonic signal by the EMAT; the circuit needs to provide enough current to enable the electromagnet to generate enough magnetic field and ensure that the EMAT can excite the ultrasonic signal; in addition, in order to verify the influence of different excitation signals on the performance of the EMAT, an electromagnet excitation amplifying circuit needs to be designed to amplify different types of signals.
5. The detection system based on the electromagnet type electromagnetic acoustic transducer as claimed in claim 1, wherein: the two-channel signal acquisition circuit is used for acquiring an ultrasonic signal received by the EMAT and a magnetic field signal of the electromagnet in the system respectively; the circuit design is carried out according to the characteristics of two paths of signals, and the amplitude of the ultrasonic signal is small and is a millivolt signal.
6. A detection system based on an electro-magnet type electro-magnetic acoustic transducer as claimed in claim 1, characterized in that: the filter is a passive low-pass filter, a 7-order Butterworth filter is adopted, the-3 dB bandwidth is 30MHz, and when the cut-off frequency is 80MHz, the attenuation is 47.5 dB.
7. A detection system based on an electro-magnet type electro-magnetic acoustic transducer as claimed in claim 1, characterized in that: the EMAT power amplification circuit with high power and high noise ratio consists of a power circuit, a driving circuit and a power output circuit; the power output circuit comprises a field effect transistor amplifying circuit, a switch control circuit and an output transformer part; the THS4151 differential circuit is adopted to realize signal differential amplification, signal buffering and current amplification are realized through the buffer BUF634 and the driving tube IRF510, and then voltage is amplified and the load limit current value is increased through the N-channel enhancement type field effect tube STP32N 06L.
8. A detection system based on an electro-magnet type electro-magnetic acoustic transducer as claimed in claim 1, characterized in that: the electromagnet power amplifying circuit adopts 36 high-capacity capacitors for charging and discharging, so that the output signal reaches the maximum value instantly; the design adopts an N-channel enhancement mode field effect transistor IRFZ44N as an output switch and uses TC4428 as a driver of a MOSFET tube.
9. A detection system based on an electro-magnet type electro-magnetic acoustic transducer as claimed in claim 1, characterized in that: according to the double-channel sampling circuit, two-stage program control amplification is adopted in the ultrasonic signal acquisition circuit part, an isolation amplitude limiting circuit is added at the signal output end to clamp voltage, and a high-pass RC filter is used for removing direct-current components.
10. A detection system based on an electro-magnet type electro-magnetic acoustic transducer as claimed in claim 1, characterized in that: the dual-channel sampling circuit utilizes 2V reference voltage to design an attenuation circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110557909.7A CN113325086A (en) | 2021-05-21 | 2021-05-21 | Detection system based on electromagnet type electromagnetic acoustic transducer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110557909.7A CN113325086A (en) | 2021-05-21 | 2021-05-21 | Detection system based on electromagnet type electromagnetic acoustic transducer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113325086A true CN113325086A (en) | 2021-08-31 |
Family
ID=77416383
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110557909.7A Pending CN113325086A (en) | 2021-05-21 | 2021-05-21 | Detection system based on electromagnet type electromagnetic acoustic transducer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113325086A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116800212A (en) * | 2023-08-23 | 2023-09-22 | 中北大学 | Gain-adjustable non-contact ultrasonic receiving signal processing circuit with clamping function |
| CN117723639A (en) * | 2023-12-19 | 2024-03-19 | 中国计量科学研究院 | Ultrasonic flaw detector verification calibrating device |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6311558B1 (en) * | 1998-03-23 | 2001-11-06 | The United States Of America As Represented By The Secretary Of Commerce | Ultrasonic strain gage using a motorized electromagnetic acoustic transducer |
| US20090084185A1 (en) * | 2007-09-27 | 2009-04-02 | Baker Hughes Incorporated | Electromagnetic acoustic transducer with cross-talk elimination |
| CN103486960A (en) * | 2013-05-07 | 2014-01-01 | 中国人民解放军海军工程大学 | Ultrasonic, vortex and EMAT integrated lossless thickness tester and method thereof |
| CN203443924U (en) * | 2013-07-18 | 2014-02-19 | 厦门艾帝尔电子科技有限公司 | Electromagnetic ultrasonic detection imaging system |
| CN103630608A (en) * | 2013-12-06 | 2014-03-12 | 天津工业大学 | Driving power supply device with high-impedance electromagnetic coil |
| CN210090383U (en) * | 2019-01-26 | 2020-02-18 | 北京工业大学 | Dual-channel high-frequency pulse excitation receiving board card based on PXI-to-serial port communication |
-
2021
- 2021-05-21 CN CN202110557909.7A patent/CN113325086A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6311558B1 (en) * | 1998-03-23 | 2001-11-06 | The United States Of America As Represented By The Secretary Of Commerce | Ultrasonic strain gage using a motorized electromagnetic acoustic transducer |
| US20090084185A1 (en) * | 2007-09-27 | 2009-04-02 | Baker Hughes Incorporated | Electromagnetic acoustic transducer with cross-talk elimination |
| CN103486960A (en) * | 2013-05-07 | 2014-01-01 | 中国人民解放军海军工程大学 | Ultrasonic, vortex and EMAT integrated lossless thickness tester and method thereof |
| CN203443924U (en) * | 2013-07-18 | 2014-02-19 | 厦门艾帝尔电子科技有限公司 | Electromagnetic ultrasonic detection imaging system |
| CN103630608A (en) * | 2013-12-06 | 2014-03-12 | 天津工业大学 | Driving power supply device with high-impedance electromagnetic coil |
| CN210090383U (en) * | 2019-01-26 | 2020-02-18 | 北京工业大学 | Dual-channel high-frequency pulse excitation receiving board card based on PXI-to-serial port communication |
Non-Patent Citations (1)
| Title |
|---|
| 郑阳 等: "基于吸盘式脉冲电磁铁的EMAT实验研究", 《传感技术学报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116800212A (en) * | 2023-08-23 | 2023-09-22 | 中北大学 | Gain-adjustable non-contact ultrasonic receiving signal processing circuit with clamping function |
| CN116800212B (en) * | 2023-08-23 | 2023-11-03 | 中北大学 | Gain-adjustable non-contact ultrasonic receiving signal processing circuit with clamping function |
| CN117723639A (en) * | 2023-12-19 | 2024-03-19 | 中国计量科学研究院 | Ultrasonic flaw detector verification calibrating device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113325086A (en) | Detection system based on electromagnet type electromagnetic acoustic transducer | |
| EP2661329B1 (en) | Improvements in or relating to ultrasound generating apparatus, and methods for generating ultrasound | |
| CN103412049B (en) | A kind of high temperature steam injection defect of pipeline monitoring method | |
| Svilainis et al. | Efficient high voltage pulser for piezoelectric air coupled transducer | |
| CN102364336A (en) | Ultrasonic wave sensor for pile supersonic wave detection | |
| Ramos et al. | Improvement in transient piezoelectric responses of NDE transceivers using selective damping and tuning networks | |
| CN101576537A (en) | Ultrasound phased array exciting bank | |
| CN2842393Y (en) | Material internal-stress supersonic measuring device | |
| CN100573613C (en) | A kind of analog ultrasonic wave earthquake signal physical excitation, receiving system and method thereof | |
| US7515019B2 (en) | Non-contact position sensor with sonic waveguide | |
| CN109060206A (en) | A kind of ferrimagnet stress measurement device and method | |
| CN115856094A (en) | Multi-channel ultrasonic guided wave detection system based on embedded computer module | |
| Wei et al. | Design of full bridge high voltage pulser for sandwiched piezoelectric ultrasonic transducers used in long rail detection | |
| CN202075264U (en) | Ultrasonic sensor for ultrasonic pile foundation detection | |
| Svilainis et al. | Investigation of the half bridge and transformer push–pull pulser topologies for ultrasonic transducer excitation | |
| CN106483526B (en) | Non-blind area ultrasonic ranging probe and ranging method | |
| US8721550B2 (en) | High voltage ultrasound transmitter with symmetrical high and low side drivers comprising stacked transistors and fast discharge | |
| CN106556641A (en) | A kind of XC6S type control systems of NEXT series of products | |
| Jain et al. | Design and development of ultrasonic bipolar square-wave pulser for non-destructive testing of concrete structures | |
| Svilainis et al. | Optimization of the ultrasonic excitation stage | |
| CN109827651A (en) | The acoustic velocity measurement device and method of a kind of ultrasonic wave in quartz glass | |
| CN110346003B (en) | Signal excitation and acquisition circuit of gas ultrasonic flowmeter | |
| Tarpara et al. | Lossless and lossy modeling of ultrasonic imaging system for immersion applications: Simulation and experimentation | |
| CN220473443U (en) | Electromagnetic ultrasonic detection system for surface defects of antenna wheel rail | |
| Kong et al. | Design of transmitting and receiving circuit of ultrasonic transducer based on STM32 |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210831 |
|
| RJ01 | Rejection of invention patent application after publication |