Journal articles: 'Underwater acoustic research'

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Viola, Salvatore, and Giorgio Riccobene. "15 years of acoustic detection studies at INFN." EPJ Web of Conferences 216 (2019): 01002. http://dx.doi.org/10.1051/epjconf/201921601002.

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Since the early 2000s, thanks to national, regional and European projects, a number of abyssal detectors equipped with acoustic sensors have been installed and operated by INFN in two cabled submarine research infrastructures off Eastern Sicily. The INFN’s interest in underwater acoustics arises from the need to develop an acoustic positioning system for the KN3NeT telescope and to study the possibility of neutrino acoustic detection. Theuse of innovative technologies for data acquisition and transmission systems have enabled the first long-term studies on the deep marine environment of the Ionian Sea with a variety of lines of research. Data acquired through the INFN underwater infrastructures have allowed the continuous monitoring of the underwater acoustic noise and several studies on cetacean species present in the area and on seismic sources . An overview of the main activities of INFN on detection and localization of underwater acoustic sources will be presented.

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Akyildiz, Ian F., Dario Pompili, and Tommaso Melodia. "Underwater acoustic sensor networks: research challenges." Ad Hoc Networks 3, no. 3 (May 2005): 257–79. http://dx.doi.org/10.1016/j.adhoc.2005.01.004.

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Li, Fulong, Xiaohong Shen, Ling Wang, and Haiyan Wang. "Research of Mobile Underwater Acoustic Communication of M-Ary Combining FDM and Piecewise-LFM." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 4 (August 2019): 704–13. http://dx.doi.org/10.1051/jnwpu/20193740704.

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Aiming at the countering doppler shift, a mobile underwater acoustic communication scheme of M-ary via FDM-PLFM is proposed. The cross-correlation between piecewise linear frequency modulation(PLFM) and traditional LFM signal is analyzed based on the cross-correlation function. Combining with frequency division multiplexing(FDM), the spectrum utilization of traditional underwater acoustic LFM communication scheme is improved. With the underwater acoustic LFM communication scheme, the new scheme does not require the doppler frequency shift compensation at the low doppler shift. The simulation results show that the present scheme has lower bit error rate than that for the traditional underwater acoustic M-ary LFM communication method under higher data rate conditions.

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Liu, Tong Qing, Guang Jie Han, Chuan Zhu, and Chen Yu Zhang. "Application Research on Aqua-Sim for Underwater Acoustic Sensor Networks." Advanced Materials Research 605-607 (December 2012): 1046–49. http://dx.doi.org/10.4028/www.scientific.net/amr.605-607.1046.

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In this paper, we present a simulator based on NS2 for Underwater Acoustic Sensor Networks (UASNs), named Aqua-Sim, which simulates the attenuation of underwater acoustic channels and the collision behaviors effectively. In addition, Aqua-Sim supports 3D network deployment and provides some MAC and routing protocols. Through communication between two nodes and localization of unknown nodes, the application examples of Aqua-Sim are shown. We also present the graphical user interface of Aqua-3D using an example application.

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Wang, Yuan, Zhou Mo Zeng, Yi Bo Li, Wen Zhang, and Hao Feng. "Research on Doppler and Channel Estimation for Multicarrier Spread Spectrum Underwater Acoustic Communication System." Advanced Materials Research 1079-1080 (December 2014): 752–56. http://dx.doi.org/10.4028/www.scientific.net/amr.1079-1080.752.

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Spreadspectrum orthogonal frequency-division multiplexing (SS-OFDM), which appliesspread spectrum technique into OFDM, performs robustly in severely multipathfading underwater channels. However, this technology is sensitive to thefrequency shift. Furthermore, communication in underwater acoustic (UWA)channels is more vulnerable to Doppler effect than other wireless channels dueto the low speed of acoustic signal propagation. It presents challenges forcommunication between underwater mobile nodes. Therefore, accurate Dopplerfrequency shift estimation and compensation is important. Aself-designed receiver structure for SS-OFDM system including a novel Dopplerscale estimation method and channel estimation via compressed sensing method isproposed. The simulation and experimental results offer strong proofs for ourscheme to be a viable option for acoustic communication between underwatermobile nodes and compressed sensing method outperforms the conventionalleast-squares (LS) method in channel estimation.

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Zhang, Minghong, and Xinwei Luo. "Underwater Acoustic Target Recognition Based on Generative Adversarial Network Data Augmentation." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 2 (August 1, 2021): 4558–64. http://dx.doi.org/10.3397/in-2021-2737.

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Underwater acoustic target recognition is an important aspect of underwater acoustic research. In recent years, machine learning has been developed continuously, which is widely and effectively applied in underwater acoustic target recognition. In order to acquire good recognition results and reduce the problem of overfitting, Adequate data sets are essential. However, underwater acoustic samples are relatively rare, which has a certain impact on recognition accuracy. In this paper, in addition of the traditional audio data augmentation method, a new method of data augmentation using generative adversarial network is proposed, which uses generator and discriminator to learn the characteristics of underwater acoustic samples, so as to generate reliable underwater acoustic signals to expand the training data set. The expanded data set is input into the deep neural network, and the transfer learning method is applied to further reduce the impact caused by small samples by fixing part of the pre-trained parameters. The experimental results show that the recognition result of this method is better than the general underwater acoustic recognition method, and the effectiveness of this method is verified.

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Kozaczka, Eugeniusz, Jacek Domagalski, and Ignacy Gloza. "Investigation of the underwater noise produced by ships by means of intensity method." Polish Maritime Research 17, no. 3 (January 1, 2010): 26–36. http://dx.doi.org/10.2478/v10012-010-0025-0.

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Investigation of the underwater noise produced by ships by means of intensity method This paper presents results of research on spectral structure of underwater noise acoustic field radiated into water by selected ships moving in shallow waters. Underwater acoustic field of ships in motion is associated with acoustic activity of ship mechanisms and equipment under work. Vibration energy radiated by the mechanisms and devices is transmitted by ship structural elements to surrounding water where it is propagated in the form of acoustic waves of a wide frequency band. In this paper are presented results of the research on propagation of energy of acoustic waves in the near fiel, obtained from acoustic pressure measurements by means of two sensors located close to each other.

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Zhao, Xinsa, Peng Yang, Rongrong Zhao, and Jianning Han. "Research on acoustic conduction mechanism of underwater acoustic channel based on metamaterials." AIP Advances 10, no. 11 (November 1, 2020): 115321. http://dx.doi.org/10.1063/5.0030198.

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Bruno, Michael, Alexander Sutin, Kil Woo Chung, Alexander Sedunov, Nikolay Sedunov, Hady Salloum, Hans Graber, and Paul Mallas. "Satellite Imaging and Passive Acoustics in Layered Approach for Small Boat Detection and Classification." Marine Technology Society Journal 45, no. 3 (May 1, 2011): 77–87. http://dx.doi.org/10.4031/mtsj.45.3.10.

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AbstractThe research being conducted in the Center for Secure and Resilient Maritime Commerce, a Department of Homeland Security National Center of Excellence for Port Security, examines some basic science issues and emerging technologies to improve the security of ports and inland waterways as well as coastal and offshore operations. This research follows a layered approach, utilizing above-water and underwater surveillance techniques. The investigated layers include satellite-based wide-area surveillance, high-frequency radar systems providing over-the-horizon monitoring, and nearshore and harbor passive acoustic surveillance. In this paper, we present a brief review of the Stevens research in passive acoustics aimed at achieving underwater and surface targets detection, classification, and tracking. The passive acoustic data were combined with satellite imagery provided by the University of Miami CSTARS facility’s electro-optical and synthetic aperture radar satellite imaging capabilities. Advantages of concurrent use of satellite imaging and passive acoustics for maritime domain awareness are analyzed.

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Zhang, Kai, De Shi Wang, Peng Wang, and Yi Qun Du. "Research on the Broadband Dual-Excited Underwater Acoustic Transducer." Advanced Engineering Forum 2-3 (December 2011): 144–47. http://dx.doi.org/10.4028/www.scientific.net/aef.2-3.144.

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The performance of bandwidth and transmitting voltage response to the piezoelectric dual-excited underwater acoustic transducer are studied by FEM software ANSYS in the paper. At first, the mechanism of the dual-excited transducer is analyzed, once this is done, The FEM models with different axial dimension of the piezoelectric stack and the mid mass, Al and steel are specified for the material of mid mass respectively. the calculated curves are contrasted, the results were found that the appropriate proportion of the mid-mass to the stack will broaden the bandwidth and enhance the transmitting voltage response, the increase of the thickness of the mid-mass will reduce the transmitting voltage response, and the bandwidth can be expanded to 13kHz, the resonance frequency has shifted to a higher value, it ranges from 34kHz to 46kHz. The results show that one octave bandwidth could be achieved and provide support for the next production and experiment of the broadband underwater acoustic transducer.

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Zhu, Yun Hang, and Zhi Hui Deng. "The Application of RAKE Receiving Technology in the Underwater SS Communication." Applied Mechanics and Materials 513-517 (February 2014): 4248–52. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.4248.

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In recent years, the strategic significance of the oceans is growing as well as its research and development needs. The underwater wireless communication is becoming more and more important. The underwater acoustic communication is one of the few mediums which can conduct the underwater transmission over a long distance, and the multipath effect is the major obstacle of affecting the systems high speed and high reliability. The characteristics of underwater acoustic fading and coherent multi-path channel are studied, and the model of underwater acoustic spreading spectrum (SS) communication system is established. The affect of coding technique on the systems performance are analyzed in detail. The improved RAKE receiving technical solution is put forward, whose simulation analysis and data in different combining ways are given. It is proved that the scheme can better solve the problem of multipath interference in underwater acoustic transmission.

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Gu, Jung-Eun, Sang Hwa Jung, Joongu Kang, and Hyoseop Woo. "Analysis for Underwater Sound on Natural River Habitat." E3S Web of Conferences 40 (2018): 02047. http://dx.doi.org/10.1051/e3sconf/20184002047.

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A riffle-pool structure is a representative physical structure of bed in rivers. The change in the physical parameter of the habitat could lead to changes in the sound environment of rivers, which are expressed by underwater acoustics. This change in underwater sound affects fish habitat. In this study, the changes of underwater acoustics were analyzed according to the change of pool-riffle sequence in a natural river. And the correlation between underwater acoustics and hydraulic characteristics was investigated. The survey for underwater acoustics was performed in the Namdae stream where is in Gangwon province. This stream belongs to the Han River basin and the river length is 39.01 km and the catchment area is 127.56 km2. The Namdae stream is a river that accounts for more than 70% of salmon returning to South Korea. The spawning salmon will return to this area around November after growing in the Bering Sea. It is important to manage the fish habitat in this river so there is a lot of research on the enhancement of fish habitat. Hydraulic characteristics were changed by the river bed structure. In this study, we investigated the relationship between underwater acoustic characteristics and hydraulic factors such as riverbed material, flow rate and water depth of each habitat type at 12 sites. The characteristics of underwater acoustic differed relative to different hydraulic factors of the two habitats, which is riffle and pool. The sound pressure level of riffles was relatively higher than that of the pools due to bed materials, shallow depth and high water velocity of riffles. In the future, it is considered that the underwater sound can be utilized as a parameter to evaluate the physical habitat environment of the river.

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Yang, Haesang, Keunhwa Lee, Youngmin Choo, and Kookhyun Kim. "Underwater Acoustic Research Trends with Machine Learning: General Background." Journal of Ocean Engineering and Technology 34, no. 2 (April 30, 2020): 147–54. http://dx.doi.org/10.26748/ksoe.2020.015.

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Peng, Yi, Yu Ping Liu, Hua Long, and Yu Bing Shao. "The Research of Cross-Layer Architecture for Cognitive UACN." Applied Mechanics and Materials 291-294 (February 2013): 2885–88. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.2885.

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Underwater acoustic communication network (UACN) has been considered as one of the main technologies for underwater communication. But underwater environmental is complex, water is a worse communication medium than the air, and in limited bandwidth. Thus, it is necessary to explore higher communication and network intelligence such as cognitive radio (CR) in UACN. In this paper, a concept of environment-adaptive CR-based UACN is proposed. Furthermore, the design of cross-layer network architecture, cognitive system processing cycle and the obstacle of CR-based UACN realization are described and discussed.

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Arsene, Delicia, Claudia Borda, Larisa Butu, Marinela Marinescu, Victor Popovici, and Mihai Arsene. "Experimental Research and Modeling of the Underwater Sound in Marine Environment." Applied Mechanics and Materials 430 (September 2013): 285–89. http://dx.doi.org/10.4028/www.scientific.net/amm.430.285.

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The paper presents a modeling of the acoustic field emitted by a rig tender located offshore exploration in the Black Sea. Are presented measuring system, experimental context, the types of noise that participate in the overall noise budget and the conditions in which measurements were made, also are mentioned and the project established through were measured the parameters and were defined devices which these measurements were made. Measurement system used is adaptable, allowing dynamic measurements and operative analysis of the acquired data. Measurement methodology was determined by an acoustic project, which was set to be purchased both: sizes and ways of interpreting them. Modeling acoustic field shows that the maximum acoustic impact area, below 120 dB re 1μPa criterion (proposed and accepted by Marine Directive) was extended to 3-5Km distance around the ship. It is expected to produce adverse effects on the marine habitat and on the underwater life.

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Yu, Yang, Jie Shi, Ke He, and Peng Han. "The Control Packet Collision Avoidance Algorithm for the Underwater Multichannel MAC Protocols via Time-Frequency Masking." Discrete Dynamics in Nature and Society 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/2437615.

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Establishing high-speed and reliable underwater acoustic networks among multiunmanned underwater vehicles (UUVs) is basic to realize cooperative and intelligent control among different UUVs. Nevertheless, different from terrestrial network, the propagation speed of the underwater acoustic network is 1500 m/s, which makes the design of the underwater acoustic network MAC protocols a big challenge. In accordance with multichannel MAC protocols, data packets and control packets are transferred through different channels, which lowers the adverse effect of acoustic network and gradually becomes the popular issues of underwater acoustic networks MAC protocol research. In this paper, we proposed a control packet collision avoidance algorithm utilizing time-frequency masking to deal with the control packets collision in the control channel. This algorithm is based on the scarcity of the noncoherent underwater acoustic communication signals, which regards collision avoiding as separation of the mixtures of communication signals from different nodes. We first measure the W-Disjoint Orthogonality of the MFSK signals and the simulation result demonstrates that there exists time-frequency mask which can separate the source signals from the mixture of the communication signals. Then we present a pairwise hydrophones separation system based on deep networks and the location information of the nodes. Consequently, the time-frequency mask can be estimated.

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Wu, Jinqiu, Gang Qiao, and Xiaofei Qi. "The Research on Improved Companding Transformation for Reducing PAPR in Underwater Acoustic OFDM Communication System." Discrete Dynamics in Nature and Society 2016 (2016): 1–9. http://dx.doi.org/10.1155/2016/3167483.

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To solve the problem of the high peak-to-average power ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) for the underwater acoustic communication system, the paper offers a method of reducing PAPR which combines the amplitude limiting and the improved nonlinear transformation. Traditional amplitude limiting technique can reduce PAPR in OFDM system effectively, at the cost of reducing the bit error rate (BER). However the companding transformation has far less computation complexity than SLM or PTS technologies and can improve the BER performance compared to the amplitude limiting technique simultaneously. The paper combines these two kinds of techniques, takes full use of advantages of the two method, and puts forward a low-complexity scheme choosing parameters that are more appropriate to the underwater acoustic field, with the result of improved BER performance even in lower SNR. Both simulation and experiment results show that the new method which combines clipping and companding transformation can effectively reduce the PAPR in the underwater acoustic OFDM communication system and improve the BER performance simultaneously.

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Liu, Shu, Qi Li, Dajing Shang, Rui Tang, and Qingming Zhang. "Measurement of Underwater Acoustic Energy Radiated by Single Raindrops." Sensors 21, no. 8 (April 11, 2021): 2687. http://dx.doi.org/10.3390/s21082687.

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Underwater noise produced by rainfall is an important component of underwater ambient noise. For example, the existence of rainfall noise causes strong disturbances to sonar performance. The underwater noise produced by a single raindrop is the basis of rainfall noise. Therefore, it is necessary to study the associated underwater noise when drops strike the water surface. Previous research focused primarily on the sound pressure and frequency spectrum of underwater noise from single raindrops, but the study on its sound energy is insufficient. The purpose of this paper is to propose a method for predicting the acoustic energy generated by raindrops of any diameter. Here, a formula was derived to calculate the underwater sound energy radiated by single raindrops based on a dipole radiation pattern. A series of experiments were conducted to measure the underwater sound energy in a 15 m × 9 m × 6 m reverberation tank filled with tap water. The analysis of the acoustic energy characteristics and conversion efficiency from kinetic to acoustic energy helped develop the model to predict the average underwater sound energy radiated by single raindrops. Using this model, the total underwater sound energy of all raindrops during a rainfall event can be predicted based on the drop size distribution.

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Liu, Meng Ran, Ze Ming Jian, Hong Liu, Xiao Peng Song, and Guo Jun Zhang. "Experiment Research on Array Grouped by MEMS Vector Hydrophone." Key Engineering Materials 609-610 (April 2014): 927–31. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.927.

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As a new type of underwater acoustic sensors,the principle of the MEMS hydrophone is introduced in this paper.MUSIC is a algorithm for estimating the parameter of the signal and it has a high resolution.In order to verify DOA estimation performance of MEMS vector array,experiment has been done.the experiments results showed that the MEMS vector array can achieve DOA estimation and track the underwater moving target.thus,it is concluded the feasibility of the MEMS vector array.

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Ju, Yang, Zhengxian Wei, Li Huangfu, and Feng Xiao. "A New Low SNR Underwater Acoustic Signal Classification Method Based on Intrinsic Modal Features Maintaining Dimensionality Reduction." Polish Maritime Research 27, no. 2 (June 1, 2020): 187–98. http://dx.doi.org/10.2478/pomr-2020-0040.

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AbstractThe classification of low signal-to-noise ratio (SNR) underwater acoustic signals in complex acoustic environments and increasingly small target radiation noise is a hot research topic.. This paper proposes a new method for signal processing—low SNR underwater acoustic signal classification method (LSUASC)—based on intrinsic modal features maintaining dimensionality reduction. Using the LSUASC method, the underwater acoustic signal was first transformed with the Hilbert-Huang Transform (HHT) and the intrinsic mode was extracted. the intrinsic mode was then transformed into a corresponding Mel-frequency cepstrum coefficient (MFCC) to form a multidimensional feature vector of the low SNR acoustic signal. Next, a semi-supervised fuzzy rough Laplacian Eigenmap (SSFRLE) method was proposed to perform manifold dimension reduction (local sparse and discrete features of underwater acoustic signals can be maintained in the dimension reduction process) and principal component analysis (PCA) was adopted in the process of dimension reduction to define the reduced dimension adaptively. Finally, Fuzzy C-Means (FCMs), which are able to classify data with weak features was adopted to cluster the signal features after dimensionality reduction. The experimental results presented here show that the LSUASC method is able to classify low SNR underwater acoustic signals with high accuracy.

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Liu, Yachen, Pengcheng Wang, Dehong Tian, Haixin Sun, Jie Qi, and Ruiping Song. "Research on Degree Distribution Optimization of LT Codes." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, no. 3 (June 2020): 627–33. http://dx.doi.org/10.1051/jnwpu/20203830627.

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LT code, as a channel coding scheme with good adaptability to the channel, has a stable performance in data transmission of underwater acoustic communication. In the case of large decoding overhead, the LT code can reach the ideal bit error rate(BER), but when the length of the encoded data is short, its coding and decoding performance is not ideal. LT code was applied to underwater acoustic communication by combining with orthogonal frequency division multiplexing (OFDM), and a LT-OFDM system was constructed. To improve the performance of LT code in the case of short code length, a method for degree distribution optimization was proposed on the objective of minimizing BER and minimizing average coding degree. Simulation and sea trial results show that under the same BER this method can optimize the system, transform 7%-22% conversion, and reduce the complexity of coding and decoding.

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Yang, Haesang, Keunhwa Lee, Youngmin Choo, and Kookhyun Kim. "Underwater Acoustic Research Trends with Machine Learning: Passive SONAR Applications." Journal of Ocean Engineering and Technology 34, no. 3 (June 30, 2020): 227–36. http://dx.doi.org/10.26748/ksoe.2020.017.

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Yang, Haesang, Sung-Hoon Byun, Keunhwa Lee, Youngmin Choo, and Kookhyun Kim. "Underwater Acoustic Research Trends with Machine Learning: Active SONAR Applications." Journal of Ocean Engineering and Technology 34, no. 4 (August 31, 2020): 277–84. http://dx.doi.org/10.26748/ksoe.2020.018.

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Ni, Xingjie, Yong Zhao, and Jian Yang. "Research of a novel fiber Bragg grating underwater acoustic sensor." Sensors and Actuators A: Physical 138, no. 1 (July 2007): 76–80. http://dx.doi.org/10.1016/j.sna.2007.04.055.

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Lv, Zhichao, Haozhong Wang, and Yiqi Bai. "Research on spatiotemporal fluctuation characteristics of underwater acoustic communication signals." Journal of the Acoustical Society of America 148, no. 4 (October 2020): 2769. http://dx.doi.org/10.1121/1.5147708.

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Tang, Nvzhi, Qian Zeng, Dongyan Luo, Qinyun Xu, and Haiyang Hu. "Research on Development and Application of Underwater Acoustic Communication System." Journal of Physics: Conference Series 1617 (August 2020): 012036. http://dx.doi.org/10.1088/1742-6596/1617/1/012036.

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Yun-Xiang Guo, Xuan-An Song, Rui-Qing Zhang, and Hui Li. "Research on Underwater Acoustic Communication System Based on OFDM-OAM." Automatic Control and Computer Sciences 54, no. 6 (November 2020): 541–48. http://dx.doi.org/10.3103/s0146411620060048.

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Hu, Gang, Kejun Wang, Yuan Peng, Mengran Qiu, Jianfei Shi, and Liangliang Liu. "Deep Learning Methods for Underwater Target Feature Extraction and Recognition." Computational Intelligence and Neuroscience 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/1214301.

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The classification and recognition technology of underwater acoustic signal were always an important research content in the field of underwater acoustic signal processing. Currently, wavelet transform, Hilbert-Huang transform, and Mel frequency cepstral coefficients are used as a method of underwater acoustic signal feature extraction. In this paper, a method for feature extraction and identification of underwater noise data based on CNN and ELM is proposed. An automatic feature extraction method of underwater acoustic signals is proposed using depth convolution network. An underwater target recognition classifier is based on extreme learning machine. Although convolution neural networks can execute both feature extraction and classification, their function mainly relies on a full connection layer, which is trained by gradient descent-based; the generalization ability is limited and suboptimal, so an extreme learning machine (ELM) was used in classification stage. Firstly, CNN learns deep and robust features, followed by the removing of the fully connected layers. Then ELM fed with the CNN features is used as the classifier to conduct an excellent classification. Experiments on the actual data set of civil ships obtained 93.04% recognition rate; compared to the traditional Mel frequency cepstral coefficients and Hilbert-Huang feature, recognition rate greatly improved.

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Abdallah, Adel, Zhang Chaozhu, and Zhong Zhi. "Investigation on the Effect of Underwater Acoustic Pressure on the Fundamental Mode of Hollow-Core Photonic Bandgap Fibers." International Journal of Optics 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/815967.

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Recently, microstructured optical fibers have become the subject of extensive research as they can be employed in many civilian and military applications. One of the recent areas of research is to enhance the normalized responsivity (NR) to acoustic pressure of the optical fiber hydrophones by replacing the conventional single mode fibers (SMFs) with hollow-core photonic bandgap fibers (HC-PBFs). However, this needs further investigation. In order to fully understand the feasibility of using HC-PBFs as acoustic pressure sensors and in underwater communication systems, it is important to study their modal properties in this environment. In this paper, the finite element solver (FES) COMSOL Multiphysics is used to study the effect of underwater acoustic pressure on the effective refractive indexneffof the fundamental mode and discuss its contribution to NR. Besides, we investigate, for the first time to our knowledge, the effect of underwater acoustic pressure on the effective areaAeffand the numerical aperture (NA) of the HC-PBF.

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Stojanovic, Milica, and Lee Freitag. "Recent Trends in Underwater Acoustic Communications." Marine Technology Society Journal 47, no. 5 (September 1, 2013): 45–50. http://dx.doi.org/10.4031/mtsj.47.5.9.

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AbstractAdvances in underwater acoustic communications technology are being enabled by more access to in-water data and an infusion of new techniques, researchers, and students. In-water data collection is being made possible by robust funding in the United States, the European Union, and other countries, typically to multiorganization consortia working on both physical and network layer research. At the physical layer, single and multicarrier modulation methods continue to be refined, with a focus on both low signal-to-noise ratio, low-rate and high signal-to-noise ratio, high-rate data links. Establishment of performance metrics for adaptive equalizers and other parts of the physical layer continue, and recent work on high-fidelity channel models that mimic the effects of small-scale ocean processes indicates that progress is being made.Research in undersea acoustic networks continues to gain momentum as well, with multiple options available for integrating acoustic propagation models with network simulation, providing common frameworks for basing network design. The combination of these recent advances, plus continued interest by maritime science and industry in wireless communications, means that the field is poised to make new commercial breakthroughs in the next several years.

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Ling-Guo, Zhu, Zhao An-Bang, Liu Wen-zhang, Han Jing, Wang Shu-tao, and Ma Zhong-cheng. "Experimental Study on Echo Characteristics of Multistatic Large-Scale Underwater Complex Target." Mathematical Problems in Engineering 2018 (June 12, 2018): 1–12. http://dx.doi.org/10.1155/2018/7852795.

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Target acoustic scattering is the primary characteristic of target echo stealth performance, and it is an important sign of the viability of large-scale complex targets underwater. In a test band, owing to the superposition of scattered waves and the elastic echo produced by shells, liquid tanks, partition plates, ribs, etc., a target exhibits an extremely complex echo phenomenon. Accurate measurement and evaluation of the acoustic scattering characteristics of underwater complex targets can be achieved via experimental research on the echo characteristics of large-scale scaled models. In this study, the contribution and regularity of the strong reflection source of underwater complex targets in various azimuths, structures, and locations were analyzed quantitatively as a basis for in-depth research and understanding of the echo characteristics of underwater complex targets.

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Oliveira, António José, Bruno Miguel Ferreira, and Nuno Alexandre Cruz. "A Performance Analysis of Feature Extraction Algorithms for Acoustic Image-Based Underwater Navigation." Journal of Marine Science and Engineering 9, no. 4 (March 28, 2021): 361. http://dx.doi.org/10.3390/jmse9040361.

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In underwater navigation, sonars are useful sensing devices for operation in confined or structured environments, enabling the detection and identification of underwater environmental features through the acquisition of acoustic images. Nonetheless, in these environments, several problems affect their performance, such as background noise and multiple secondary echoes. In recent years, research has been conducted regarding the application of feature extraction algorithms to underwater acoustic images, with the purpose of achieving a robust solution for the detection and matching of environmental features. However, since these algorithms were originally developed for optical image analysis, conclusions in the literature diverge regarding their suitability to acoustic imaging. This article presents a detailed comparison between the SURF (Speeded-Up Robust Features), ORB (Oriented FAST and Rotated BRIEF), BRISK (Binary Robust Invariant Scalable Keypoints), and SURF-Harris algorithms, based on the performance of their feature detection and description procedures, when applied to acoustic data collected by an autonomous underwater vehicle. Several characteristics of the studied algorithms were taken into account, such as feature point distribution, feature detection accuracy, and feature description robustness. A possible adaptation of feature extraction procedures to acoustic imaging is further explored through the implementation of a feature selection module. The performed comparison has also provided evidence that further development of the current feature description methodologies might be required for underwater acoustic image analysis.

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Zhang, Yan Bing, Chun Yu Ren, and Xi Zhu. "The Research of Acoustic Characteristic from a Submerged Viscoelastic Functionally Graded Materials." Advanced Materials Research 602-604 (December 2012): 132–36. http://dx.doi.org/10.4028/www.scientific.net/amr.602-604.132.

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In this paper, we designed a FGM which can be used as the cover of underwater target and research its mid-low frequency acoustic characteristic just as reflection and absorption coefficient. Based on transfer matrix method, we research the FGM acoustic reflection and absorption coefficient change with the variation of constituent material property, number of hierarchy, and volume fraction. We found that its reflection and absorption coefficient are determinated by material property and volume fraction, and could be equivalent to multi-layer composite structure with specific number of layers to address acoustic problems. If elastic layer added, both acoustic characteristic and mechanics characteristic could be improved, which contributes to the research and design of structure/acoustic stealth FGM.

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Murgod, Tejaswini R., and S. Meenakshi Sundaram. "Survey on underwater optical wireless communication: perspectives and challenges." Indonesian Journal of Electrical Engineering and Computer Science 13, no. 1 (January 1, 2019): 138. http://dx.doi.org/10.11591/ijeecs.v13.i1.pp138-146.

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<div><p class="Affiliation">The demand for underwater communication is growing at a faster pace since few decades. Maximizing the communication performance and building efficient network architecture for underwater communication is a challenging task. Due to the reduced bandwidth, high error rate, noise, propagation delay, water currents and increased cost in the network topology, the existing communication techniques are not feasible for underwater communication. Research in high speed underwater transmission technology has become a primary need in today’s world. By using underwater acoustic sensor network high transmission distance can be achieved but with lower data rates, high power consumption, larger delays and with higher cost. Underwater Optical Communication can be used to increase data rates and lower delays but it suffers from high attenuation due to which it cannot be used for data transfer over larger distances. Research in the area of hybrid sensor networks is a challenging task and has many open research challenges, which needs to be solved. In this paper we discuss the various architectures of underwater communication. A comparative study is made on different routing protocols and localization algorithms. The challenges faced by acoustic and optical communication are also discussed.</p></div>

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Liu, Yan Jun, Xing Wang Sun, Yu Li, and Ji Bin Liu. "The Progress of Bionic AUV Stealth Technology Research." Advanced Materials Research 591-593 (November 2012): 381–84. http://dx.doi.org/10.4028/www.scientific.net/amr.591-593.381.

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With the development of high technology war. Bionic autonomous underwater vehicle has become a popular issue these years, To Achieve better concealment, the stealth technology is the most difficult problem that must be solved. This paper briefly introduces the principle methods to keep the AUV quiet and difficult to be found, the advantages and disadvantages of all these extraction methods were analyzed. The stealth technology of underwater vehicle refers to the means that make the enemy’s sonar can’t detect their own location or shorten the distance, mainly including two aspects: noise control and acoustic antagonism. Finally, the development tendency of Bionic AUV stealth technology is provided.

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Yan, Huichao, and Linmei Zhang. "Denoising of MEMS Vector Hydrophone Signal Based on Empirical Model Wavelet Method." Proceedings 15, no. 1 (July 8, 2019): 11. http://dx.doi.org/10.3390/proceedings2019015011.

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Underwater acoustic technology is a major method in current ocean research and exploration, which support the detection of seabed environment and marine life. However, the detection accuracy is directly affected by the quality of underwater acoustic signals collected by hydrophones. Hydrophones are efficient and important tools for collecting underwater acoustic signals. The collected signals of hydrophone often contain lots kinds of noise as the work environment is unknown and complex. Traditional signal denoising methods, such as wavelet analysis and empirical mode decomposition, product unsatisfied results of denoising. In this paper, a denoising method combining wavelet threshold processing and empirical mode decomposition is proposed, and correlation analysis is added in the signal reconstruction process. Finally, the experiment proves that the proposed denoising method has a better denoising performance. With the employment of the proposed method, the underwater acoustic signals turn smoothly and the signal drift of the collected hydroacoustic signal is improved. Comparing the signal spectrums of other methods, the spectral energy of the proposed denoising method is more concentrated, and almost no energy attenuation occurred.

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Cristea, Ovidiu, Florențiu Deliu, Nicolae Badara, and Octavian Tarabuta. "Experimental Model for Data Transmission in the Underwater Environment." International conference KNOWLEDGE-BASED ORGANIZATION 24, no. 3 (June 1, 2018): 32–37. http://dx.doi.org/10.1515/kbo-2018-0133.

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Abstract Communications applications in the underwater environment have recently developed a considerable development due to the demand for underwater research with Robot Underwater Vehicle (ROV). The most important aspects addressed by researchers are related to the speed and distance of data transmissions. In most cases, this data signal may be electromagnetic, optical or acoustic. The first two cases have limitations on the distance of the communication channel due to signal attenuation. That is why the acoustic field can be considered the favorite in this choice. In this case, the limitations of use are given by the acoustic field propagation, which depends on the temperature, salinity and pressure of the underwater environment and the result is the variation of the propagation speed. The influence of frequency on attenuation and reverberation are important factors limiting the use of the acoustic field. Based on these considerations, the paper presents an experimental transceiver model of data transmission using Frequency Shift Keying (FSK), modulation with phase discontinuity for transmitting and receiving commands at the speed of 2kbits / s

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Li Peng, 李鹏, 赵扬 Zhao Yang, 周志权 Zhou Zhiquan, 张鹏辉 Zhang Penghui, 白雪 Bai Xue, and 马健 Ma Jian. "一种跨介质的空中-水下激光致声探测技术研究." Infrared and Laser Engineering 50, no. 5 (2021): 20200310. http://dx.doi.org/10.3788/irla20200310.

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Legusha, F., and Yu Popov. "Numerical simulation of acoustic signal propagation in underwater acoustic duct." Transactions of the Krylov State Research Centre 2, no. 396 (May 21, 2021): 122–33. http://dx.doi.org/10.24937/2542-2324-2021-2-396-122-133.

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Object and purpose of research. The progress in numerical simulation methods significantly widens the capabilities of theoretical analysis in the tasks requiring extensive calculations and input data sets, like sound propagation at sea. This paper discusses the feasibility of a numerical model describing the physics of acoustic signal propagation in a deep-water channel. Materials and methods. Acoustic signal calculation is performed as per the ray-path theory with a numerical model taking into account depth-wise variations of sound velocity and seabed parameters. Main results. It was shown that depending on the vertical distribution of sound speed, the source depth and distance, the acoustic wave propagation direction can change over significant range of angles the in vertical plane. In this regard it is advisable to calculate the real target force of an object of complex geometry not only from heading angle in horizontal plane but also in terms of the possible range of angles in the vertical plane. Conclusion. Model-analyzed angles range of long-range wave propagation may be used for change estimation of object target force characteristics. Practical significance of the study lies in improving the methods of calculation of the real target force of complex shape objects in terms of state-of the art capabilities of simulating the propagation of acoustic signals conditions in the ocean.

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Li, Jiangqiao, Li Jiang, Fujian Yu, Ye Zhang, and Kun Gao. "Research on improving measurement accuracy of acoustic transfer function of underwater vehicle." MATEC Web of Conferences 336 (2021): 01006. http://dx.doi.org/10.1051/matecconf/202133601006.

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To address the problem that acoustic transfer functions with underwater platforms cannot be measured accurately, this paper presents a method based on phase compensation to improve the accuracy of acoustic transfer function measurements on underwater platforms. The time-domain impulse response signals with multiple cycles are first collected and intercepted, and then their phase differences are estimated using the least-squares method, and phase compensation is used to align the phases of all the signals, and then the impulse response signals are weighted and averaged over all the impulse response signals to cancel out the random noise. The water pool test proves that this method reduces the measurement random noise while obtaining a high-fidelity time domain transfer function, which effectively improves the signal-to-noise ratio of the measurement. The method adopts only one measurement signal, and without changing the measurement system, the random noise is cancelled out by the in-phase superposition of the multi-cycle impulse response signals to avoid the nonlinear distortion of the measurement results.

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Manik, Henry M. "Acoustic Observation of Zooplankton Using High Frequency Sonar (Observasi Akustik Zooplankton Menggunakan Sonar Frekuensi Tinggi)." ILMU KELAUTAN: Indonesian Journal of Marine Sciences 20, no. 2 (June 2, 2015): 61. http://dx.doi.org/10.14710/ik.ijms.20.2.61-72.

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Underwater acoustic sampling techniques provide an advantage over traditional net-sampling for zooplankton research. The research presents a methodology for extracting both biological and physical information from high frequency sonar. These methods can easily provide the information that will improve our understanding of the spatial and temporal distribution of zooplankton. Measured acoustic data converted into biological organisms and numerical physics-based scattering models were used in this research. The numerical backscattering process was modeled using the Distorted-Wave Born Approximation (DWBA) to predict the amount of sound scattered by a weakly scattering animal. Both acoustic measurement and DWBA modeled scattering patterns showed that acoustic scattering levels are highly dependent on zooplankton orientation. The acoustic backscattering from zooplankton depends on the material properties (i.e. the sound speed and density of the zooplankton), the shape and size, and the orientation relative to the incident acoustic wave. DWBA model significantly improve the accuracy and precision of zooplankton acoustic surveys. Zooplankton data measurement and DWBA model analysis provide a basis for future acoustical studies.

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Lembke, Chad, Susan Lowerre-Barbieri, David Mann, and J. Christopher Taylor. "Using Three Acoustic Technologies on Underwater Gliders to Survey Fish." Marine Technology Society Journal 52, no. 6 (November 1, 2018): 39–52. http://dx.doi.org/10.4031/mtsj.52.6.1.

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AbstractAutonomous platforms and vehicles are a growing component of the ocean research fleet, producing data sets crucial to our understanding of oceanographic and fishery ecosystem processes. One emerging tool for making these measurements is underwater gliders that autonomously sample the water column for weeks to months at a time. Although originally designed to measure temperature and salinity, underwater gliders can now support a myriad of sensors. For the demonstration project described within, three complementary acoustic technologies were integrated into an underwater glider for mapping fish on the continental shelf: an acoustic telemetry receiver, a passive acoustic monitoring recorder, and a fisheries echosounder.The demonstration project was designed to evaluate the effectiveness of each sensing technology. Sixty-one fish were implanted with acoustic tags near the Gulfstream Natural Gas pipeline in the eastern Gulf of Mexico in advance of planned underwater glider missions. The glider was deployed four times over 12 months, with all three acoustic technologies to traverse the pipeline and surrounding habitat. Glider detections were compared to detections of fish at moored acoustic tag telemetry receivers and passive acoustic recorders co-located at the tagged fish locations. All three technologies identified fish along the targeted hard-bottom pipeline habitat, as well as previously uncharted areas of hard-bottom reef. The results of this study demonstrate the utility of gliders integrated with acoustic sensors as a potential tool to identify areas that merit deeper investigation to assess fish stocks.

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Wang, Peng, and Yi Qun Du. "Research on a Co-Vibrating Vector Hydrophone with Central Fixed Structure." Advanced Materials Research 346 (September 2011): 835–41. http://dx.doi.org/10.4028/www.scientific.net/amr.346.835.

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Suspension system of a co-vibrating vector hydrophone need be designed carefully to reach the requirement of underwater acoustic measurement. Condition of vibration sensing of co-vibrating vector hydrophone is researched separately based on acoustic theory and mechanical vibration theory. A co-vibrating vector hydrophone with central fixed structure had been analyzed. The simplified model and equivalent circuit model of the proposed design were built for the analysis. The voltage response of the hydrophone to acoustic particle velocity is derived, and improvement of voltage sensitivity based on cymbal transducer is performed. Simulation result shows the design of vector hydrophone with central fixed structure can satisfied the requirements of acoustic measurement, and cymbal transducer can improve the response voltage sensitivity further.

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MR Christhuraj, Manikandan TT, Saravanan M, Rajeev Sukumaran,. "MAC Layer Communication Protocol design using Stochastic Network Calculusfor Underwater Agriculture Farming." Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 5 (April 11, 2021): 223–30. http://dx.doi.org/10.17762/turcomat.v12i5.879.

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: The hazardous in seawater network, channel utilization, and MAC layer protocol design induces the research challenges and opportunities of underwater acoustic communications, particularly in terms of throughput and transmission delay. In this research work, we propose the delay-tolerant MAC protocol with collision avoidance. Under_Water Medium Access control and Collision Avoidance -Wireless protocol (UWMACA-W) proposed for underwater Agriculture Farming. This research work also has compared the performance of the UWMACA-Wireless protocol with and without SNC. The growth of the plants inside the bubble can be exchanged to the base station by using the UWMACA-wireless protocol and also increases interface efficiency by taking account of the underwater acoustic channel's long delay time, as well as fixing the issues related to uncovered terminal issues. UWMACA-W method has higher performance than MACA-Wireless protocol, according to simulation testing on Riverbed modeler.

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Yang, Haesang, Keunhwa Lee, Youngmin Choo, and Kookhyun Kim. "Underwater Acoustic Research Trends with Machine Learning: Ocean Parameter Inversion Applications." Journal of Ocean Engineering and Technology 34, no. 5 (October 31, 2020): 371–76. http://dx.doi.org/10.26748/ksoe.2020.016.

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WANG Deqing, XU Ru, HU Xiaoyi, XU Fang, LIU Hui, and CHEN Huabin. "Research on Cluster-based MAC Protocol for Underwater Acoustic Sensor Networks." Journal of Convergence Information Technology 7, no. 6 (April 30, 2012): 202–10. http://dx.doi.org/10.4156/jcit.vol7.issue6.25.

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Meng, Jie, Yong Jie Wang, Lei Cai, and Ran Wei. "Research on the Combination of Underwater Acoustic Countermeasure Equipments Against Torpedo." MATEC Web of Conferences 40 (2016): 02018. http://dx.doi.org/10.1051/matecconf/20164002018.

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Campo-Valera, María, Ivan Felis-Enguix, and Isidro Villó-Pérez. "Signal Processing for Parametric Acoustic Sources Applied to Underwater Communication." Sensors 20, no. 20 (October 17, 2020): 5878. http://dx.doi.org/10.3390/s20205878.

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For years, in the field of underwater acoustics, a line of research with special relevance for applications of environmental monitoring and maritime security has been developed that explores the possibilities of non-linear phenomena of sound propagation, especially referring to the so-called parametric effect or self-modulation. This article shows the results of using a new modulation technique based on sine-sweep signals, compared to classical modulations (FSK and PSK). For each of these modulations, a series of 16-bit strings of information with different frequencies and durations have been performed, with the same 200 kHz carrier wave. All of them have been tested in the Hydroacoustic Laboratory of the CTN and, through the application of cross-correlation processing, the limitations and improvements of this novel processing technique have been evaluated. This allows reaching better limits in discrimination of bits and signal-to-noise ratio used in underwater parametric acoustic communications.

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Deng, Yueyue, Pierre-Philippe J. Beaujean, Edgar An, and Edward Carlson. "Task Allocation and Path Planning for Collaborative Autonomous Underwater Vehicles Operating through an Underwater Acoustic Network." Journal of Robotics 2013 (2013): 1–15. http://dx.doi.org/10.1155/2013/483095.

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Dynamic and unstructured multiple cooperative autonomous underwater vehicle (AUV) missions are highly complex operations, and task allocation and path planning are made significantly more challenging under realistic underwater acoustic communication constraints. This paper presents a solution for the task allocation and path planning for multiple AUVs under marginal acoustic communication conditions: a location-aided task allocation framework (LAAF) algorithm for multitarget task assignment and the grid-based multiobjective optimal programming (GMOOP) mathematical model for finding an optimal vehicle command decision given a set of objectives and constraints. Both the LAAF and GMOOP algorithms are well suited in poor acoustic network condition and dynamic environment. Our research is based on an existing mobile ad hoc network underwater acoustic simulator and blind flooding routing protocol. Simulation results demonstrate that the location-aided auction strategy performs significantly better than the well-accepted auction algorithm developed by Bertsekas in terms of task-allocation time and network bandwidth consumption. We also demonstrate that the GMOOP path-planning technique provides an efficient method for executing multiobjective tasks by cooperative agents with limited communication capabilities. This is in contrast to existing multiobjective action selection methods that are limited to networks where constant, reliable communication is assumed to be available.

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Onur, T. O. "Investigation of Parameters Affecting Underwater Communication Channel." Journal of Engineering Sciences 7, no. 1 (2020): F39—F44. http://dx.doi.org/10.21272/jes.2020.7(1).f4.

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Underwater communication has become a widely studied area in recent years and showed great potential to be an area of research. Acoustic communication is often preferred in underwater communication due to its suitability for an underwater diffusion environment. However, in underwater communication, the physical and chemical properties of the water environment affect sound propagation. Therefore, determining and examining parameters affecting channel performance in underwater communication plays an essential role in inefficient communication. In this study, the effects of salinity, depth, noise, temperature, and frequency parameters for the underwater channel model are examined. By determining the effects of these parameters on spherical and cylindrical propagation, suitable propagation geometry and parameter values for an efficient channel are investigated. In light of the results obtained, in case of studying in a limited area, the path and absorption losses can be reduced by selecting cylindrical propagation as a geometrical propagation model, thereby an efficient channel model can be formed. Keywords: cylindrical propagation, spherical propagation, underwater communication channel, acoustic communication, path loss, absorption loss.

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Journal articles on the topic 'Underwater acoustic research'

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