Hangzhou Applied Acoustics Research Institute

Hangzhou, China

Hangzhou Applied Acoustics Research Institute

Hangzhou, China

Time filter

Source Type

Liu J.,Hangzhou Applied Acoustics Research Institute
2016 IEEE/OES China Ocean Acoustics Symposium, COA 2016 | Year: 2016

Over the past several years, Hangzhou Applied Acoustics Research Institute(HAARI) has developed the ring transducer, including the air-backed ring transducer(ABRT) and free-flooded ring transducer(FFRT). A previous paper [1] described a kind of transmit-receive air-backed ring transducer with radially poled ceramic. This paper reports on our successful efforts to develop a broadband segmented free-flooded ring transducer with a circumferentially poled ceramic. Broadband response is achieved by coupling the cavity resonance mode and the circumferential resonance mode. The maximum diameter of the transducer is 90mm (without mounting base). As a transmit-receive transducer, the maximum of the Transmitting Voltage Response (TVR) is 141.3 dB//μPa@1m/V, @12.8kHz. The frequency band with transmitting response decreasing 3dB is from 9.6kHz to 18.4kHz. The maximum of the Receiving Voltage Response (RVS)in free field is -179 dB//V/μPa, @13.2kHz. The frequency band width receiving response decreasing 3.3dB is from 8.6kHz to 18.8kHz. The transducer shows great promise as a broadband, high efficiency, high-power underwater acoustic transceiver for deep water applications in excess of several thousand meters and with an omi-directionally beam pattern in horizon. © 2016 IEEE.


Yang Y.,Hangzhou Applied Acoustics Research Institute | Jiao J.,Hangzhou Applied Acoustics Research Institute
2016 IEEE/OES China Ocean Acoustics Symposium, COA 2016 | Year: 2016

The sounding method and accuracy of multi-beam bathymetric sonars are being continuously researched, and many traditional multi-beam bathymetric algorithms have been proposed, such as: the Energy Centre method, the WMT method, the BDI method, etc. Some of these methods have a high precision of sounding in the mirror area, while some have a high precision of sounding in the non- mirror area. If we combine these methods and apply them to high-frequency shallow-water multi-beam sonar, the precision of sounding reaches a satisfactory level. Besides the sounding precision, the sounding resolution (the number of sounding points) is also an important indicator for multi-beam bathymetric sonar. The sounding resolution of a traditional bathymetric algorithm mainly depends on the number of pre-formed beams, which restricts the improvement of sounding resolution. In this paper, differential phase technology will be applied to broadband multi-beam bathymetric sonar, which not only ensures the accuracy of sounding, but also greatly improves the sounding resolution by dozens of times or even a hundred times as compared to a traditional bathymetric algorithm. Hence, more detailed acoustic images can be obtained without increasing the frequency of multi-beam bathymetric sonar. This is possible by using differential phase technology for underwater topography, which is advantageous for small target detection. The paper also analyzes various important factors which affect the differential phase technique, such as additive noise, baseline de-correlation and beam footprint of the seabed. In addition, it also gives the theoretical curve of sounding accuracy changing with the signal pulse width, SNR, grazing angle and other factors. Finally, we find that even under high SNR conditions, differential phase technology is still able to maintain a good sounding performance, even when we reduce the number of received array elements. This lays a good foundation for studying low frequency multi-beam bathymetric sonar. © 2016 IEEE.


Wang Q.,Hangzhou Applied Acoustics Research Institute | Wang L.,Hangzhou Applied Acoustics Research Institute
2016 IEEE/OES China Ocean Acoustics Symposium, COA 2016 | Year: 2016

Conventional energy detection (CED) is the optimal signal detection in uncorrelated noise field. Subband peak energy detection (SPED) further improves the display resolution of CED by exploiting the spatial coherence of the energy peaks. However, under low signal to noise ratio (SNR) condition or where there are few snapshots, the performance of weak target detection submerged in strong interferences by SPED is still unsatisfying. An improved SPED method is proposed in this paper. The improved SPED algorithm exploits the spatial continuity of the signal besides the spatial coherence. Restricted by the resolution of beamforming method, the local peaks of the target would not occur in the exact same azimuth for each frequency bin. By integrating these scattered peaks, the energy of the weak target will be enhanced. A double detection is then implemented to pick out the noise peaks. Experiments are conducted with simulated data to validate the effectiveness of the proposed method. Results show a better display resolution of the proposed method with a better detection performance of the relatively weak target, especially under poor conditions when the number of snapshots is small or SNR is low. © 2016 IEEE.


Yue Z.,Hangzhou Applied Acoustics Research Institute | Wang T.,Hangzhou Applied Acoustics Research Institute
2016 IEEE/OES China Ocean Acoustics Symposium, COA 2016 | Year: 2016

AUV underwater docking is an effective way to provide energy supplement and complete information exchange with an AUV, which in turn allows an AUV make long-term missions in the water and avoid the need for repeated launching and retrieval. This paper proposes a new navigation and positioning system, which measures distance by underwater acoustic communication and by USBL. It can be used for underwater AUV remote positioning and guiding, so that an AUV can find the underwater feeder station in order to complete energy supply and exchange of information. The system consists of a T/R transducer at the end of the AUV; an electronic cabin within the chamber of the AUV, and, a T/R transducer USBL array and watertight electronic cabin at the end of underwater feeder station. For the hardware, the T/R transducers operating band is 10 kHz ∼ 14kHz with overflow structure; there is a USBL array of conical structures; and, an electronic compartment which uses DSP, FPGA, MSP430 joint architecture. For the algorithms, the underwater acoustic communication equipment uses both LFM signal head and DSSS communication algorithms in order to obtain distance measurement results. The USBL array uses M sequence modulated signals emitted from the AUV terminal in order to measure direction. The system performance was tested in a lake, In the static case, the range accuracy was 0.2m ± 0.05%, and the orientation of the measurement accuracy is 0.3°. In the dynamic case, the positioning results were compared with GPS Real-time results, and their positioning track fitted well with each other. © 2016 IEEE.


Zhang K.,Hangzhou Applied Acoustics Research Institute
Proceedings of the 2015 Symposium on Piezoelectricity, Acoustic Waves and Device Applications, SPAWDA 2015 | Year: 2015

There are many advantages of broadband transducers, such as reducing of signal distortion, widening the security about information transmission, reducing the ratio of false codes. The use of eight 33 mode single crystal pieces, a thin light beryllium alloy head mass and a thick heavy tungsten alloy tail mass can expand the bandwidth of the middle-frequency transducer. The one-fourth finite element model of transducer was set up with ANSYS software and the structure of the transducer was optimized. A final transducer was designed, fabricated and measured, and its longitudinal size is about 21mm. The bandwidth of the transducer is 17 kHz-120 kHz, in which the ripple of the transmitting voltage response does not exceed ±5dB. There are several conclusions from the research: the bandwidth of tonpilz transducers can be expanded by the use of single crystal pieces, beryllium alloy head mass and tungsten alloy tail mass; and it gives a method to achieve the broad-band projecting performance of middle-frequency transducers. © 2015 IEEE.


Bai L.-L.,Hangzhou Applied Acoustics Research Institute
Proceedings of the 2012 Symposium on Piezoelectricity, Acoustic Waves and Device Applications, SPAWDA 2012 | Year: 2012

According to Berktay the far-field solution of parametric array, self-demodulatory sound pressure is proportional to squared of envelope function to the second derivative of the time. The excitation input signals of parametric array were designed and analyzed. A parameter array is measured under the different excitation signals. The results show that: (1) When the input signals is single-sideband amplitude modulatory signal the harmonic distortion of the sound field is relatively small compared to the double sideband amplitude modulated signal and the difference frequency wave acoustic source level is higher; (2) The difference frequency wave source level will increase rapidly with increase of input power of the parametric array. But too much power may cause the power amplifier to produce nonlinear, thus the harmonic amplitude increase and the conversion efficiency will be lower. © 2012 IEEE.


Zheng Z.-Y.,Hangzhou Applied Acoustics Research Institute
Proceedings of the 2012 Symposium on Piezoelectricity, Acoustic Waves and Device Applications, SPAWDA 2012 | Year: 2012

The equivalent circuit model of piezoelectric ceramic pillar transducer with matching layer material is proposed, and the applicability of this model in the U-shape transducer array is discussed. The vibration character and directivity pattern of the transducer are analyzed by the finite element method. The manufactured U-shape transducer array has verified feasibility of the piezoelectric ceramic pillar transducer with matching layer design. The broadband and high power density characters of such design are suitable for high frequency broadband acoustic emission with special directivity. © 2012 IEEE.


Zhang K.,Hangzhou Applied Acoustics Research Institute
Proceedings of the 2012 Symposium on Piezoelectricity, Acoustic Waves and Device Applications, SPAWDA 2012 | Year: 2012

There many advantages of broadband transducers, such as reducing of signal distortion, widening the security about information transmission, reducing the ratio of false codes. The combine of piezoelectric pillars and dual matching layers can expand the bandwidth of the high-frequency transducer. The one-eighth finite element model of transducer was set up with ANSYS software and the structure of the transducer was optimized. A final transducer was designed, which used the first thickness mode, the second thickness mode and the third thickness mode. The bandwidth of the transducer is 47kHz-159kHz, in which the ripple of the transmitting voltage response does not exceed ±3dB. There are several conclusions from the research: the bandwidth of pillar transducers can be expanded by the first thickness mode, the second thickness mode and the third thickness mode, and it gives a method to achieve the broad-band projecting performance of high-frequency transducers. © 2012 IEEE.


Xu X.-R.,Hangzhou Applied Acoustics Research Institute
Proceedings of the 2012 Symposium on Piezoelectricity, Acoustic Waves and Device Applications, SPAWDA 2012 | Year: 2012

In this paper, a new structure with a perforated electrode design in free-flooded 33-mode ring transducer is proposed. The FEM is utilized to simulate the performance of the transducer, and several design parameters are optimized to achieve higher output power over a wider bandwidth. The tested performance of the manufactured transducers verify the validity of the design. The influence of different shape openings of transducer on its performance is also studied experimentally. © 2012 IEEE.


Zhang K.,Hangzhou Applied Acoustics Research Institute
Proceedings of the 2014 Symposium on Piezoelectricity, Acoustic Waves and Device Applications, SPAWDA 2014 | Year: 2014

There are many advantages of 1-3 piezocomposite transducers, such as lighter weight, lower specific acoustic impedance. The matching layer is commonly used to expand the bandwidth of composite transducers. The finite element modal of transducer was set up with ANSYS software and the structure of the transducer was optimized. A final 1-3 piezocomposite transducer was designed, which used the first thickness mode, the first lateral mode and the third thickness mode. The bandwidth of the transducer is 120kHz-470kHz, in which the ripple of the transmitting voltage response does not exceed ±5dB. There are several conclusions from the research: the bandwidth of 1-3 piezocomposite transducers can be expanded by the first thickness mode, the first lateral mode and the third thickness mode, and it gives a method to achieve the broad-band projecting performance of high-frequency transducers. © 2014 IEEE.

Loading Hangzhou Applied Acoustics Research Institute collaborators
Loading Hangzhou Applied Acoustics Research Institute collaborators