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Organizer:

Ship and Ocean Technology Research Center

Department of Engineering Science and Ocean Engineering, National Taiwan University

Co-organizer:

OceanSound Co. Inc.

Sponsors: Ministry of Science and Technology, Taiwan Office of Naval Research, USA

Office of Naval Research Global, USA

National Taiwan University, Taiwan Acoustical Society of America, USA

International Ocean and Atmosphere Research

Development Foundation, Taiwan

Editor:

Chi-Fang Chen

Mei-Yuh Shih

National Taiwan University

Published by:

National Taiwan University, Taipei, Taiwan

http:// pruac2018.esoe.ntu.edu.tw/

September 2018

i

The 6th Pacific Rim Underwater Acoustic Conference

Contents

I Information

Welcome to PRUAC2018……………………………………………. 2

General Information…………………………………………………. 3

Scientific Committee………………………………………………… 3

Local Committee…………………………………………………….. 4

Working Group………………………………………………………. 5

Plenary Speakers……………………………………………………... 6

Practical Information………………………………………………… 7

IceBreaker: Cosmos Hotel, Taipei…………………………………… 7

Conference Venue: FarGlory Hotel………………………………….. 7

Information for Presenters…………………………………………… 8

Coffee & Lunch……………………………………………………… 8

WiFi at the Venue……………………………………………………. 8

Social Events………………………………………………………….. 9

Welcome Reception………………………………………………….. 9

Two-hour Train Excursion…………………………………………… 9

Conference Banquet………………………………………………….. 9

Local Tour to Taroko National Park………………………………… 9

II. Abstracts

Ross Norman Chapman, Sounds in the Ocean: Experiments and

Measurements in Underwater Acoustics.12

Michael Porter, Laurel J. Henderson, John Peterson, Tim Duda, Arthur

Newhall, Peter Traykovski. Fully 3D Sound Propagation in the

Weymouth Fore River, with a Dry-Dock and a Ship Hull.

13

Yuanliang Ma, Yixin Yang, Yong Wang. Underwater Acoustic Sensor

Array Processing: Problems and Improving Approaches.14

Ruijie Meng, Shihong Zhou, Fenghua Li. Radial Velocity Estimation of

Moving Source Using Pressure Difference of Dual Hydrophones.15

Zhao Zhen Dong, J. Zeng, L. Ma, E. C. Shang. A Model-free Approach

for Inverting the Intrinsic Attenuationα(f) of Sea-bed Sediment.16

T. C. Yang, S. H. Huang. Deconvolved Conventional Beamforming

Applied to the SW06 and SWellEx96 Data.17

Juan Zeng, Z.D. Zhao, L. Ma, E. C. Shang. A Simple Estimation of the

Seabed Sound Speed with the Group Speed of the Critical Mode. 18

Gee-Pinn James Too, Lin-Hua Hsu, Kuan-Yuan Chen. Comparison of 19

ii


Alternative Underwater Communication Modulation Schemes in

Various Conditions.

Xiao Chuan Ma, Chao Feng. An Effective System Modeling Method

for the Reduction of Low Frequency Noise from Marine Detection

UUVs.

20

Wen Xu, Lianlong Li. 2016 Shallow-Water Experiment on Ocean

Acoustic-Dynamic Coupled Data Assimilation in South China Sea. 21

Yan Zhang, Shihong Zhou. A Range-estimation Method for Surface

Sources Based on the Characteristic of Bottom Bounced Sound in

Deep Water.

22

Zhenglin Li, Renhe Zhang, Zhiguo Hu. Sound Propagation in Deep

Water with a Sloping Bottom. 23

Shuyuan Du, Shihong Zhou, Yubo Qi . Full Wavefield Computation and

Propagation Simulations in Typical Irregular Seabottom Environment. 24

Fei-Yun Wu, Kun-de Yang, Rui Duan, Hui Li. An Improved Non-

uniform Norm Method for Sparse Channel Estimation. 25

Alexey O. Maksimov, Yu A. Polovinka. Bubble Dynamics Near an

Interface. 26

Ching-Sang Chiu, Linus Y. S. Chiu, Chi-Fang Chen, Yiing Jang Yang,

Jiann-Yuh Lou, Christopher W. Miller. Geoacoustic Properties of, and

Propagation Anisotropy Induced by, Subaqueous Sand Dunes on the

Upper-slope of the Northeastern South China Sea.

27

Ying-Tsong Lin, Underwater Sound Pressure Sensitivity in Three-

Dimensional Oceanic Environments. 28

Tiago Oliveira, Ying-Tsong Lin, Towards 3D Global Scale Underwater

Sound Modeling. 29

Linus Chiu, Ching-Sang Chiu, Chi-Fang Chen, Yiing-Jian Yang, Ruey-

Chang Wei, Andrea Chang, Acoustic Propagation Effects of

Subaqueous Sand Dune Bedforms in the South China Sea.

30

Douglas Herrod Cato, Challenges and Progress in the Study of the

Effects of Noise on Marine Life. 31

Tomonari Akamatsu, Assessment of Noise Impacts on Marine

Organisms. 32

Siddagangaiah Shashidhar, Chi-Fang Chen, Silent Winters: Long

Term Study of Fish Chorusing and Evidence of Impact of Continual

Shipping Noise on Fishes.

33

Dong-Gyun Han, Jee Woong Choi, Jungyul Na. Measurements of Pile

Driving Noise from Offshore Wind Farm Construction in Southwest

Coast of Korea.

34

iii


Roberto Racca, Graham Warner, Alexander MacGillivray, Jorge

Quijano, Melanie Austin. Calculating Marine Mammal Harassment

Zones from Hydroacoustic Measurements and Modelling of Pile

Driving Operations.

35

Pai-Ho Chiu, Ruey-Chang Wei, Hin-Kiu Mok, Keryea Soong,

Soundscape in Shallow Water of Dongsha Island, South China Sea. 36

Matthew Pine, Ding Wang, Lindsay Porter, Francis Juanes, Kexiong

Wang. Changes to the Fine-scale Habitat Use in Indo-Pacific

Humpback Dolphins in Relation to Vessel Traffic in Hong Kong SAR.

37

III Posters

Yeon-Seong Choo, Sung-Hoon Byun, Sea-Moon Kim and Keunhwa

Lee. Observation of Acoustic Echoes from Aluminum Hollow Sphere

Using a Horizontal Line Array.

39

Cheng Jiang, Wen Xu, Jianlong Li and Zhongyue Chen. Temporal-

Spatial Aggregation in Underwater Acoustic Passive Detection with A

Mobile Node.

40

Donghyeon Kim, Yonghwa Choi, Gihoon Byun, Seongil Cho and

Jeasoo Kim, Direction Finding of Snapping Shrimp Based on Δf - k

Spectrum.

41

Sehyun Lee, Keunhwa Lee, Jun-Seok Lim, Myoung-Jun Cheong.

Waveform Design for Compressive Sensing Active SONAR. 42

Wei-Lun Li, Wei-Yen Chu and Chi-Fang Chen. Dolphin Whistle

Detection. 43

Jingyao Liang, Ting Zhang, Wen Xu. Passive Localization Based on

Distributed Network via Double-Correlation Function of Opportunity

Sources.

44

Kuan-Wen Liu, and Ching-Jer Huang. Real-time Monitoring of

Underwater Sound Using a Buoy Installed with a Hydrophone 45

Raegeun Oh, Bon-Sung Gu, Taek-Lyul Song and Jee Woong Choi.

Correction of Bearing Error of Line Array Sonar System Due to

Bottom Bounced Path Signal

46

Ping-Jung Sung, and Chi-Fang Chen. Pile Driving Noise Simulation

and Analysis (Exhibition only)

Yin-Ying Fang, Chi-Fang Chen and Sheng-Ju Wu, Optimization of

Acoustic Signature Identification System for Ocean Researcher III

(OR3) (Exhibition only)

Dong Hwan Jung and J. S. Kim. Simple Method Using Zero Crossing

of Envelope for Time Delay Estimation. (Exhibition only)

iv


Presenters Index 47

Conference Program 49

1

Information

PART I

2


Welcome to PRUAC2018

Dear Participants,

May we extend our hearty welcome to you all! Welcome to Taiwan for the

PRUAC2018, the 6th Pacific Rim Underwater Acoustic Conference. We welcome the

distinguished guests and speakers from 9 countries of the world.

We are thankful to co-organizer, the Ocean Sound work together with us to make

this meeting possible. We also are thankful to the Ministry of Science and Technology

(MOST) of Taiwan, National Taiwan University, International Ocean & Atmosphere

Research Development (IOAR), and ONR (Office of Naval Research), ONRG (Office

of Naval Research Global), Acoustical Society of America (ASA) who sponsor and

support us in various aspects.

We are very blessed to have Dr. Ross Chapman, Dr. Douglas Cato and Dr. Michael

Buckingham who are worldly renowned speakers who have accepted our invitation as

plenary speakers though Dr. Buckingham due to health reason cannot make it at the end.

In the PRUAC2018, we have 26 papers from 9 countries; namely, Australia,

Canada, China, Japan, Korea, Russia, Singapore, USA and Taiwan. The papers are

mostly from the academic sector, some are from industrial sector and/or the

collaboration of the both sectors. And, their focuses are on conference theme: (1)

Underwater Noise Impacts on Marine Life and Acoustic Monitoring of Marine Life,

and, (2) Underwater Acoustic Studies in Littoral Waters.

The PRUAC2018 will give award of USD900 to top three graduate students who

compete and present posters in the event. We have received 11 contributed posters

from students of three countries. One Student Awards Committee of 12, from six

countries, chaired by Dr. Andrea Y. Y. Chang will evaluate the creativity, the design and

the speed talk of the research. We give thanks to the ASA for offering and encouraging

students this excellent chance to participate the meeting and to compete poster.

As always, we appreciate the Office of Naval Research (ONR) and Office of Naval

Research Global (ONRG) for generously support this academic and research event.

Last but most important, let us give thanks to all the participants who are of various

generations, cultures and research specialties to come from afar to join us. May we wish

your stay in Taiwan a joyous and unforgettable one.

Chi-Fang Chen

Professor

National Taiwan University, Taiwan

Chairman

3


General Information _____________________________________________

Conference Chairman

Chi-Fang Chen

Professor

National Taiwan University, Taipei, Taiwan

Scientific Committee

Chi-Fang Chen National Taiwan University, Taiwan

Tomonari Akamatsu Fisheries Research and Education Agency, Japan

Michael Buckingham Scripps Institution of Oceanography, USA

Douglas Cato University of Sydney, Australia

Ross Chapman University of Victoria, Canada

Ching Sang Chiu Naval Postgraduate School, USA

Jee Woong Choi Korea Maritime and Ocean University, Republic of Korea

Peter Dahl University of Washington, USA

Jea-soo Kim Korea Maritime and Ocean University, Republic of Korea

William Kuperman Scripps Institution of Oceanography, USA

Fenghua Li Chinese Academy of Sciences, China

Ying-Tsong Lin Woods Hole Oceanographic Institution, USA

Yuanliang Ma Northwestern Polytechnical University, China

Michael Porter Heat, Light and Sound Research, Inc., USA

Gang Qiao Harbin Engineering University, China

Roberto Racca JASCO Applied Sciences, Canada

Er-Chang Shang Chinese Academy of Sciences, China

Jeffrey Simmen Office of Naval Research Global (ONRG)

Robert Spindel University of Washington, USA

Wen Xu Zhejiang University, China

Juan Zeng Chinese Academy of Sciences, China

Renhe Zhang Chinese Academy of Sciences, China

4


Local Committee

Chi-Fang Chen National Taiwan University

Andrea Y. Y. Chang National Sun Yat-sen University

Mao-Hsiung Chiang National Taiwan University

Linus Y.S Chiu National Sun Yat-sen University

C. J. Huang National Cheng Kung University

Sheng-Fong Lin National Kaohsiung University of Science and Technology

Gee-Pinn James Too National Cheng Kung University

Jing-Fa Tsai National Taiwan University

Chung-Wu Wang Ocean Sound Co., Ltd.

Ruey-Chang Wei National Sun Yat-sen University

Wei-Cheng Yang National Taiwan University

5


Working Group

Secretary: Mei-yuh Shih

Activity Team

Ching-Tang Hung

MengFan Tsai

Yao Sung Hsu

I Yun Su

Kuan Jung Pan

Hsu Yong Hung

You Cheng Zhang

Reception Team

Ying-Rong Chen

Charlie Chiao-Ming Peng

York Chu

Yun-Dian Fan Jiang

Tai-Hua Liu

Chiu Kuan Shih

Hsiang-Hsuan Jan

Venue Team

Yen-Hsiang Huang

Peng-Kuei Chen

Hsiang-Hsuan Chao

Wei-Yen Chiu

Ping Jung Sung

Wei-Lun Li

Ming-Chou Wu

Academic Team

Shashidhar Siddagangaiah

Wendy Yin-Ying Fang

Wen-Yang Liu

Angela Hsieh

IT Team

William Hu

6


Plenary Speakers

Plenary Lecture

Ross Norman Chapman (University of Victoria,

Canada) will give lecture on Sounds in the Ocean:

Experiments and Measurements in Underwater Acoustics.

Professor Chapman is an Emeritus Faculty and Chair of

Ocean Acoustics at the University of Victoria in Victoria, British Columbia, Canada,

He is a Fellow of the Institute of Electrical and Electronic Engineers (IEEE) and the

Acoustical Society of America, and previously Editor in Chief of the IEEE Journal of

Oceanic Engineering. He has published over 150 research papers and chapters in

journals and books, and is internationally known for his work in ocean acoustics

propagation, geoacoustic inversion and ambient noise. Professor Chapman is a

founder of the PRUAC conference series, and his participation enhances the stature of

the event.

Douglas Herrod Cato (University of Sydney, Australia) will give lecture on

Challenges and Progress in the Study of the Effects of Noise on

Marine Life.

Professor Cato is an adjunct professor of the School of

Geosciences and Marine Studies Centre, University of

Sydney. His research includes underwater acoustics,

particularly the ambient noise and soundscapes of the

ocean, marine bioacoustics and the effects of noise on

marine animals. Recent work includes a project on the

effects of the noise of seismic surveys on humpback whale

behavior. He has more than 50 years’ experience in underwater

acoustics, and more than 35 years’ experience in marine bioacoustics, including

experimental work in the laboratory and at sea, and as chief scientist of many sea

experiments.

7


Practical Information

IceBreaker: Cosmos Hotel, Taipei

The IceBreaker of PRUAC2018 will take place in Cheer Banquet Room of the

Cosmos Hotel Taipei. The Cosmos Hotel Taipei is conveniently located next to the

M3 exit of MRT’s Taipei Station stop, at the heart of Taipei’s well establish public

transit system. Since its opening in 1979, Cosmos Hotel has been the hotel of choice

for many international tourists and business travelers, as well as a popular destination

for corporate meetings and group seminars.

Conference Venue: FarGlory Hotel

The conference will be held at the Farglory Hotel of HuaLien, Taiwan. Farglory

Hotel stands 220 meters high and covers dozens of hectares. With the mountains to

one side and the ocean to the other, Farglory Hotel is also close to Farglory Ocean

Park, Hualien. Be it of the nearby Mugua Stream, the Central Mountains, Hualien

City, or the Pacific Ocean, the hotel offers an amazingly clear vista.

The meeting and poster exhibition will take place in Windsor House; coffee breaks

and exhibition will take place in front of the Victoria House.

8


Information for Presenters

The meeting room, Windsor House, of FarGlory Hotel is equipped with projector,

computer and laser pointer. One of the organizer staff will assist you. You may

update and/or download your presentation PowerPoint 15 minutes before the start of

each session.

Coffee & Meals

Drinks, coffee and snacks will be provided on the banquet foyer, in front of the

Windsor House.

Breakfast will be served with buffet, lunch and dinner meals are mostly of Chinese

cuisine. And, we will be served by sitting around the table.

WiFi at the Venue

WiFi is available in the FarGlory Hotel. Conference participants can get access to

Internet anywhere in the hotel.

Meeting Room (Windsor House) & Banquet Foyer

9


Social Events

Welcome Reception

Sunday, 2 September 2018, 13:30-14:00: The welcome reception (IceBreaker) will

be held at Cheer Hall of the Cosmos Hotel Taipei. Registration will be done from

13:30-14:00, the Welcome (IceBreaker) will be followed, 14:00-16:00. Light drinks,

coffee and snacks will be served. Friends from local as well as other parts of the

world will get to know each other, you will meet with old as well as new friends.

Two-hour Train Excursion

The scenery along the road between Taipei to HuaLien is very pretty. After the

IceBreaker, we will all take, around two hours, the same train carriage to conference

venue. On the train, we can read, play card, rest and make new friends.

Conference Banquet

Monday, 3 September 2018, 18:30-21:00, Victoria House

We will have dinner banquet in the house of the Victorian style architecture. Chinese

cuisine will be served. Many honorable guests will be invited to share their insights

and close relationship with the PRUAC. You are encouraged to say a few words to all

the participants.

Local Tour to Taroko National Park

Tuesday, September 4, 2018, 10:00-18:00

We will take a local tour to Taroko National Park which is one of the nine national

Parks in Taiwan. This park is named after the Taroko Gorge. This Gorge and its

surrounding area are well known for their abundant supply of marble, leading to its

nickname, ‘The Marble Gorge’. There are

many trails, tunnels, temples and cliffs in the

park. We will have an unusual and exciting

experiences from this tour.

11


ABSTRACTS

Part II

12


Sounds in the Ocean: Experiments and Measurements in Underwater Acoustics

Ross Chapman

[email protected]

University of Victoria, Canada

ABSTRACT

For this lecture, professor Chapman will talk about the objective of the presentation

is two-fold: first to show what we have learned about sound transmission in the ocean

from the results of simple experiments, and second, to show the linkage between ocean

acoustics and knowledge about ocean properties and structure from oceanographic

research. Our interpretation of results from acoustic experiments has to be framed

within the reality of physical processes in and properties of the ocean that determine

the nature of sound propagation.

The plan for the lecture is to show examples of data from experiments with sound

sources and receivers, and then describe the conclusions that can be drawn about the

nature of sound transmission. Results are shown from experiments to measure

transmission loss in deep oceans that were crucial in providing new knowledge about

the ocean as an acoustic lens that enabled sound propagation to long ranges.

Transmission loss is based on measurements of the acoustic intensity, so the

presentation then looks at the additional information that is obtained from the phase of

the sound signal. Examples are presented that illustrate the use of full field data to

enable detection of distant sound sources with arrays of hydrophones, location of sound

sources and inversion of ocean environmental properties using matched field

processing. Acoustics of shallow water environments is discussed in terms of

experimental measurements of normal modes, and examples are shown to illustrate the

use of modes for inversion of models of the ocean environment. Finally, the

presentation introduces measurements of ambient noise and describes its use as a sound

source. For each theme that is presented, reference is made to present day research

that is continuing in the theme.


Fully 3D Sound Propagation in the Weymouth Fore River,

with a Dry-Dock and a Ship Hull

*Michael B. Porter1, Laurel J. Henderson1, and John Peterson1, Tim Duda2,

Arthur Newhall2, Peter Traykovski2

*Presenter: [email protected] Heat, Light, and Sound Research, San Diego, U.S.A.

2 Woods Hole Oceanographic Institution, Woods Hole, U.S.A.

ABSTRACT

Refraction and reflection in the latitude/longitude direction (as well as depth) affect

sound propagation in certain environments. Nonlinear internal waves are an example

of an oceanographic feature that can produce dramatic effects. Seamounts and

continental slopes are examples of bathymetric features that can also matter. Still

stronger features can be found in constrained spaces such as harbors; such an

environment with its many reflecting boundaries scarcely resembles an open ocean

scenario, which is often modeled as a cylindrically symmetric medium. One anticipates

big effects as the sound rays bounce off both the bottom and the sidewalls --- it is more

like a problem in architectural acoustics.

To understand better these effects and to verify our capability to model them, we

have begun an experimental program in which a variety of environments are being

studied. The talk will report on the first site, which was in the old Quincy Shipyard of

the Weymouth Fore River. The experiment was conducted on May 25, 2018 and as of

this writing is still being analyzed. An extremely detailed bathymetric survey was done

using an autonomous surface vehicle called a Jetyak. The Jetyak was also used to tow

an acoustic source that was complemented by a source towed by another vessel. Chirps

covering the 8-34 kHz band were used to measure the impulse response of the channel.

The key initial questions for this site: 1) are 3D effects important? 2) can we model

them effectively? The acoustic modeling is being done with the BELLHOP3D beam-

tracing code that has evolved in recent years into a fairly mature model. There are few

alternatives as most ocean acoustic models assume outgoing waves and therefore

cannot treat the reflections. We will discuss our conclusions in this presentation.

13

mailto:[email protected]

14


Underwater Acoustic Sensor Array Processing: Problems and Improving Approaches

Yuanliang Ma*, Yixin Yang, and Yong Wang

*Presenter: [email protected]

School of Marine Science and Technology, Northwestern Polytechnical University,

Xi’an 710072, China

ABSTRACT

Problems and improving approaches for underwater acoustic sensor array

processing are presented based on recent progress made in our research group. The

problems concern about precise analytic solutions for arbitrarily configured arrays, high

gain processing for arrays with limited size at low frequencies, wideband requirement

and ultra-low side-lobe design of beampattern, in addition to a new concept on adaptive

arrays in changeable noise environments.

A unified framework is given in this talk by providing the theoretical solution for

arbitrarily configured sensor arrays. Supposing the noise covariance matrix is obtained,

it is feasible to decompose it into orthogonal mode vectors through Gram-Schmidt

Transform. A matrix form of the transform is deduced which facilitates to express the

inverse of the covariance matrix in an analytic form. Based on these, a series of

expressions are obtained namely the solution of optimal array weighting vector, the

optimal beam-pattern for maximum array gain, the robustness analysis of the optimal

solution etc. All above solutions are expressed in closed-form and the information

required a priori is the environmental noise covariance matrix as well as the direction

vectors of the receiving array in hand.

Following the theoretical framework above, it is feasible to find specific methods

for the mentioned problems. That is: Mode Decomposition and Synthesis method for

arbitrarily configured sensor arrays, theoretical and practical solutions for Super-

directivity, beam-pattern Side-lobe Control in mode space, Wideband Implementation

of optimal array processing, in addition to Feed-forward Adaptation to array processing

for changeable underwater acoustic environments. Tremendous computations and

simulations have been conducted together with typical array design experiments, which

confirm the merits of the solutions and technical approaches.

15


Radial Velocity Estimation of Moving Source Using Pressure Difference of Dual Hydrophones

Ruijie Meng1,2, Shihong Zhou1, *Fenghua Li1

*Presenter: [email protected] 1 State Key Laboratory of Acoustics, Institute of Acoustics,

Chinese Academy of Sciences, Beijing, 100190, China 2 University of Chinese Academy of Sciences, Beijing 100049, China

ABSTRACT

Motion velocity estimation of a moving source is very important for marine

application of common interests. This paper presents an approach to estimate the radial

velocity of moving source using dual hydrophones. The radial separation of the dual

hydrophones is required to satisfy less than one-fourth of wavelength. The enough

range or time accumulated window due to tonal source or receiver motion is also

needed. In this approach, the particle vibration velocity could be calculated according

to the pressure difference principle with the known source azimuth. The wavenumber

spectrum of normal modes can be obtained using Hankel transform from the pressure

field and the particle vibration velocity, respectively. From the ratios of their peak

amplitudes corresponding to the separated normal mode, the source radial velocity

could be estimated through the relationship between the theoretical and hypothetical

wavenumbers. Simulations show that the relative error of radial velocity estimation is

less than 10% when the SNR is greater than 0 dB. Using the data from the SWellEx’96

sea trial in the sea area of San Diego in California conducted by University of

California, the estimated radial velocities of the moving source match the real values

from GPS measurement.

16


A Model-free Approach for Inverting the Intrinsic Attenuation α(f) of Sea-bed Sediment

*Z.D. Zhao, J. Zeng, L. Ma and E.C. Shang


Key laboratory of underwater acoustics environment, Institute of Acoustics, CAS,

China

ABSTRACT

Inverting the sea-bed geoacoustic (GA) properties from measurements of ocean

acoustic field has been a very active research area in the past four decades, of which the

most difficult part consists in the attenuation α(f) and its frequency dependency. So far,

most of the inverting results are obtained from model-based approach, i.e. a GA bottom

model needs to be assumed afore, which may lead to critical distortion of α(f) due to

model-mismatching. In order to overcome the model-mismatching problem and to

invert the intrinsic α(f), we propose a model-free approach depending on the

perturbation-based integral expression of modal attenuation βm(f). The model-free

reflective phase-shifting parameter P(f) of the bottom as a priori information combined

with WKB approximation of the modal function ψm(z) make the whole integrand

known. Sensitivity analysis and numerical calculation show that an accurate enough

estimation of the intrinsic attenuation α(f) can be obtained. Preliminary experimental

result at site-B of Yellow Sea (2018) is reported, and in the frequency band of 100-

1000Hz, the inverted α(f) clearly reveals a nearly linear frequency dependency.

17


Deconvolved Conventional Beamforming Applied to the SW06 and SWellEx96 Data

*T. C. Yang, S. H. Huang


Ocean College, Zhejiang University, Zhoushan, Zhejiang, China

ABSTRACT

Horizontal arrays are often used to detect/separate a weak signal and estimate its

direction of arrival among many loud interfering sources and ambient noise.

Conventional beamforming (CBF) is robust but suffers from fat beams and high level

sidelobes. High resolution beamforming such as minimum-variance distortionless-

response (MVDR) yields narrow beam widths and low sidelobe levels but is sensitive

to signal mismatch and requires many snapshots of data to estimate the signal

covariance matrix, which can be a problem for a moving source. Deconvolution

algorithm used in image de-blurring was applied to the conventional beam power of a

uniform line array (spaced at half-wavelength) to avoid the instability problems of

common deconvolution methods (T. C. Yang, IEEE J. Oceanic Eng., 43, 160-172,

2018). The deconvolved beam output yields narrow beams, and low sidelobe levels

similar to, or better than MVDR and at the same time retains the robustness of CBF. It

yields a higher output signal-to-noise ratio than MVDR for isotropic noise. The method

is applied to the horizontal array data collected during the SW06 and SWellEx96

experiments. Bearing time record are created to compare the performance of various

beamforming methods.

18


A Simple Estimation of the Seabed Sound Speed with the Group Speed of the Critical Mode

*J. Zeng, Z.D. Zhao, L. Ma and E.C. Shang


Key laboratory of underwater acoustics environment, Institute of Acoustics, CAS,

China

ABSTRACT

The critical mode (the mode with the highest order) penetrates into the seabed the

deepest and then is the most sensitive mode to the varying of the seabed geacoustics

parameters (seabed sound speed, density and attenuation). The quantities related to the

critical mode, such as the grazing angle and group speed, have the born advantage in

inverting the seabed geoacoustics parameters. In this paper, a simple method of the

estimation of the seabed sound speed is discussed, which is based on the group speed

of the critical mode. In the Pekeris waveguide, when the frequency is high enough, the

seabed sound speed 𝑐𝑏 has a simple relationship with the water sound speed 𝑐𝑤 and

the group speed of the critical mode 𝑣𝑔𝑀 as 𝑐𝑏 ≈ (𝑐𝑤

2 𝑣𝑔𝑀⁄ ). The seabed sound speed

can be rapidly inferred with the knowledge of 𝑐𝑤 and 𝑣𝑔𝑀. With the warping transform

and the relationship between the warped frequency and the group speed, the group

speed of the critical mode can be directly extracted from the envelope of the warped

spectrum of the broadband signal received at close range. Both the simulation data and

the experimental data collected in January 2018 in Yellow sea of China are used to

testify the inversion. The inverted results are compared to those exploited with MFP

method and core sampling. At lower frequency band (f=100~600Hz), the inverted

sound speed has good agreement with those inverted with MFP, which is between

1570~1600m/s. At higher frequency (f=1200~2500Hz), the inverted sound speed

agrees with core sampling results well, which is between 1530~1550m/s.

19


Comparison of Alternative Underwater Communication Modulation Schemes in

Various Conditions

*Gee-Pinn James Too, Li-Hua Hsu, Kuan-Yuan Chen


Department of Systems and Naval Mechatronic Engineering,

National Cheng Kung University, Tainan, Taiwan

ABSTRACT

Underwater acoustic communication (UAC) has been widely developed by

researchers. Multipath effects induce severe inter-symbol interference (ISI) in the

communication process. In the present study, three alternative communication

modulation schemes such as : Frequency Shift Keying(FSK),Phase Shift Keying(PSK)

and Orthogonal Frequency Division Multiplexing(OFDM), are used and compared with

Time Reversal Mirror(TRM) and without TRM process. Simulations and experiments

are conducted respectively at various ocean conditions. Simulations are conducted for

shallow water communication and deep sea communication. Experiments are

conducted in the testing platform of 4mX8mX175m towing tank at National Cheng

Kung University. The results indicate that by using TRM enhances SNR by 3 to 5 dB,

therefore it gives better communication, particularly for shallow communication. If

multipath effects cannot be avoided, FSK gives more consistent communication results

than PSK in shallow water communication. At low SNR condition, PSK gives better

communication than FSK. Finally, OFDM gives the fastest communication rate among

the three modulation schemes. However, OFDM is sensitive to frequency shift and

sampling rate shift.

20


An Effective System Modeling Method for the Reduction of Low Frequency Noise from Marine

Detection UUVs

Xiao Chuan MA, *Chao FENG

*Presenter: [email protected] Key Laboratory of Information Technology for AUVs, Institute of Acoustics,

University of Chinese Academy of Sciences, Beijing, China

ABSTRACT

The vibro-acoustics and modal analysis of the suspension architecture of the power system in an unmanned underwater vehicle, which is used for the researches of oceanography and marine life, are studied in this paper. The sensors carried on board for underwater acoustic detection and exploration requires strictly controlled noise level, and the self-induced noise and vibration of the UUV mainly come from the power and propulsion system. Due to the complicated undersea environment, a UUV with variable speed drive is needed. Under the circumstances, the noise level could escalate with the speeding up.

An effective noise and vibration control scheme can remarkably reduce the

radiation noise. However, the solution to the suspension architecture for the power system is usually difficult due to its component complexity. An efficient analysis method is the key to the selection of appropriate suspension architecture. The experimental method tends to be costly and time consuming. Subsystem simulations for each component is feasible, yet usually fail to meet expectations when applied to the whole system. A full system modeling method is adopted to examine the natural frequencies and mode shapes of the power system and to determine a material parameter optimized suspension scheme.

In the proposed method, the power and propulsion system is analyzed using finite element model and the suspension architecture is modeled using spring-damper elements, which will suffice to illustrate the low frequency vibro-acoustical analysis. Through the proposed full system modeling, the connection between the suspension architecture and the radiated noise is established. The operating noise is inevitable, however, the optimized suspension scheme acquired through the proposed method is proved by the experimental results to be capable of keeping the system noise at a low level for all the possible working conditions of the UUV.

21


2016 Shallow-Water Experiment on Ocean Acoustic-Dynamic Coupled Data Assimilation in

South China Sea

*Wen Xu, Jianlong Li


School of Information Science and Electronic Engineering

Key Laboratory of Ocean Observation-Imaging Testbed of Zhejiang Province

Zhejiang University, China

ABSTRACT

Ocean acoustic-dynamic coupled observation can improve the prediction accuracy

of the acoustical and oceanographic fields by assimilating the observation data such as

sound pressure, water temperature, and salinity. Such a system was integrated jointly

by Zhejiang University, Institute of Acoustics - Chinese Academy of Sciences, China

Shipbuilding Industry Corporation, Harbin Engineering University, and the Ocean

University of China. The system includes seven fixed moorings, two autonomous

underwater vehicles, and an onshore communication and data center, which involves

observations of ocean dynamical processes of different time-spatial scales and physical

mechanisms, both scalar and vector acoustical field measurements, networking based

on RF and acoustic communications, acoustic and oceanographic modeling, and data

and model integration. From May to July, 2016, a field experiment was conducted in

the northwest part of the South China Sea, with water depth of about 100 meters. The

experimental site was characterized by persistent internal tidal waves. On-site

forecasting of ocean temperature, salinity, current velocity, and acoustic pressure was

demonstrated for an area of over 60 Km by 60 Km based on the ROMS regional model.

In addition, as probably the first in the world, an acoustic temperature profiler was

installed on a surface ship and showed superior performance in tracking water-column

sound speed variation. The experiment and some preliminary data processing results

are introduced in this talk. Subsequent analyses of the acoustic and oceanographic

synchronously sampled data are expected to generate important scientific significances

of interdisciplinary research.

[Work supported by National High-Tech Program of China under Grant #

2012AA090901]

22


A Range-estimation Method for Surface Sources Based on the Characteristic of Bottom Bounced

Sound in Deep Water

*Yan Zhang and Shihong Zhou


State Key Laboratory of Acoustics, Institute of Acoustics,

Chinese Academy of Sciences, Beijing 100190, China

ABSTRACT

The rays of bottom bounced sound in deep water arrive at the receiver through the

paths hitting the bottom boundary once. It is indicated by theoretical analysis and

numerical simulation that due to the interference of multipath rays the intensity of

bottom bounced sound periodically oscillates in the frequency domain at a certain

source-receiver-range. The oscillating period is corresponding to arrival time delays of

rays and the delay time decreases with source-receiver-range increasing. Base on this

characteristic, a range-estimation method for surface sources has been presented. The

results of experimental data processing show that the range of surface sources can be

estimated effectively with a mean absolute error less than 2 kilometers.

23


Sound Propagation in Deep Water with a Sloping Bottom

*Zhenglin Li, Renhe Zhang, and Zhiguo Hu


State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of

Sciences, Beijing 100190, China

ABSTRACT

Variation of water depth have large effects on the sound propagation. It is

meaningful for SONAR application to understand the mechanism of sound propagation

in a deep water environment with complex bathymetries. An acoustic propagation

experiment for two different tracks with the flat bottom and the sloping bottom

environments was conducted in the South China Sea. The experimental results show

that the transmission losses (TLs) decrease up to about 5 dB above the slope due the

reflection of the bottom. When a sea hill with height less than 1/10 of water depth exists

at the range of sound beams incident on bottom first time, an inverted-triangle shadow

zone appears at its reflection area. The TLs increase up to 8 dB in the corresponding

area of the first shadow zone, and the abnormal TLs effects can reach to maximal depth

of 1500m. The spatial correlations for the two propagation tracks are also investigated.

The differences of the TLs and the horizontal-longitudinal correlations oscillation

patterns are explained by using the ray theory. [Work supported by the National Natural

Science Foundation of China under Grant No. 10434012 and Grant No. 41561144006]

24


Full Wavefield Computation and Propagation Simulations in Typical Irregular Seabottom

Environment

*Shuyuan Du, Shihong Zhou, Yubo Qi


State Key Laboratory of Acoustics, Institute of Acoustics,

Chinese Academy of Sciences, Beijing 100190, China

ABSTRACT

The calculation and prediction of the ocean acoustic field is the basis for

underwater applications in the marine environment. With the development of acoustics

towards low even very low frequency, it is of important theoretical and realistic

importance to calculate accurately the full-wavefield including underwater acoustics

and low-frequency seismoacoustics due to effects of elastic bottoms. This paper focuses

on clarifying the propagation mechanism of low-frequency seismoacoustics. Several

high-precision calculations of the full-wavefield in typical irregular seabottom

environment such as fluctuated layered elastic bottom, slope layered elastic seabottom,

deep sea environment with seamounts are performed. In order to get accurate results,

model mesh and grid optimization to improve the stability of spectral element method

(SEM) are performed. The excitation and propagation mechanism of seismoacoustic,

including body waves, interface wave, etc. are simulated in typical submarine

environments.

25


An Improved Non-uniform Norm Method for Sparse Channel Estimation

*Fei-Yun Wu, Kun-de Yang, Rui Duan, Hui Li


School of Marine Science and Technology, Northwestern Polytechnical University,

Xi'an, Shaanxi, China

ABSTRACT

The non-uniform norm (NN) based method exhibits its superiority such as low

computational cost and effective recovery. However, the optimization of descent

gradient is zig-zagging with small step sizes towards the minimum, thus leads to

ineffective and slow convergence. In this study, we aim to improve the convergence

rate at least without the loss of accuracy via alleviating the fluctuations of descent

directions. An accelerated strategy termed Accelerated NN (ANN) is proposed for

sparse channel estimation. ANN reuses the previous and current estimates via the

derivation of a Low Pass Filtering (LPF) operation on the noisy gradient. The LPF

filters the original gradient and prevent the large fluctuations of iterative direction

generated by the steepest gradient descent during the adaptation process. Simulations

are provided to verify the superiority and effectiveness of ANN algorithm.

26


Bubble Dynamics Near an Interface

*A. O. Maksimov, Yu. A. Polovinka

Presenter: [email protected]

Pacific Oceanological Institute, Far Eastern Branch of

The Russian Academy of Sciences, Vladivostok, 690041, Russia

ABSTRACT

The presence of gas bubbles plays an important role in the generation, scattering

and absorption of sound in a liquid. The applications of gas bubbles are diverse,

including acoustical oceanography and medical and industrial ultrasound. In the oil and

gas industry, bubble monitoring is required for acoustic remote early warnings of

``blow-out'' from offshore installations, detection of leaks from underwater gas

pipelines, and seabed monitoring. Although a great deal is known about bubble

oscillations in unbounded liquids, it is not very clear to what extent these results are

applicable to the dynamics of constrained bubbles. The present study is aimed at

investigation of bubble dynamic in the presence of bounding surfaces. Explicit

dependences of the first oscillation modes and the scattered field on bubble size,

distance to the flat boundary, and physical parameters of contacting media are obtained.

It is shown that, as the distance to the boundary decreases, dipole oscillations acquire

resonance nature and become comparable in amplitude with radial oscillations. Another

example of a confining surface is the presence of the second gas bubble. For a two-

phase flow, the subject of forced oscillations of a pair of bubbles is important because

it controls how bubbles interact with each other. The proposed approach uses a bi-

spherical coordinate system and is limited to a description of a sufficiently long-wave

acoustical field, so that the bubbles are homobaric, and the medium in the vicinity of

the bubbles can be considered incompressible. The choice of a specific coordinate

system allows the authors to take into account the internal symmetry inherent in this

problem and provides a partial summation on only the most important contributions to

the multiple scattering series. A closed form solution was derived for the scattered

acoustic field that determines its parametric dependence on bubbles sizes and the

separation distance.

27


Geoacoustic Properties of, and Propagation Anisotropy Induced by, Subaqueous Sand Dunes on

the Upper-slope of the Northeastern South China Sea

*Ching-Sang Chiu 1, Linus Y. S. Chiu 2, Chi-Fang Chen3, Yiing Jang Yang3,

Jiann-Yuh Lou4, Christopher W. Miller1

*Presenter: [email protected] 11Naval Postgraduate School, Monterey, CA, U.S.A.

2National Sun Yat-sen University, Kaohsiung, Taiwan 3National Taiwan University, Taipei, Taiwan 4R.O.C. Naval Academy, Kaohsiung, Taiwan

ABSTRACT

Very large subaqueous sand dunes have been observed on the upper continental

slope of the Northeastern South China Sea. In an effort to map the highly variable

bathymetry and to attain initial information on the geoacoustic properties, a multibeam

echo sounder (MBES) survey, grabbed sediment samples, as well as acoustic

transmissions of a 1-2 kHz and a 4-5 kHz chirp signal repeated from a towed source

that circled a moored hydrophone were carried out in May, 2013. Pertinent

geoacoustic parameters, specifically the compressional wave speed, attenuation and

layer thickness, were first estimated based on a geoacoustic inversion entailing least-

squares fitting of an ensemble of modeled 2-D transmission losses to the measured

losses in the radial sectors that are largely perpendicular to the sand dunes. In a

different and prognostic manner, Biot theory with inputs analyzed from the sediment

samples were also used to independently predict the compressional wave speed and

attenuation. The consistency between the geoacoustic inversion results and the

prognostic Biot-theory results are compared and discussed. Furthermore, with the

measured bathymetry and estimated geoacoustic parameters, the transmission loss as a

function of bearing around the towed circle were calculated using a PE propagation

model. The modeled transmission losses are compared to the measured ones to help

interpret and gain insights into the observed anisotropy of the transmission loss and its

azimuthal variance. (The research was jointly sponsored by the Ministry of Science

and Technology, Taiwan and the Office of Naval Research, USA.)


Underwater Sound Pressure Sensitivity in Three-dimensional Oceanic Environments

Ying-Tsong Lin

[email protected]

Associate Scientist with Tenure

Applied Ocean Physics & Engineering Department

Woods Hole Oceanographic Institution, U.S.A.

ABSTRACT

Underwater sound propagation in the ocean can be influenced jointly by physical

oceanographic processes, marine geological features, sub-bottom geoacoustic structure,

sea surface disturbances, biology distributions, etc.. As a result, the underwater sound

pressure field will have significant temporal and spatial variability. The primary goal

of this study is to develop a numerical scheme to determine the sound pressure

sensitivity in response to variations of index of refraction caused by changes of

environmental conditions. A sensitivity kernel is first derived from a higher-order

parabolic-equation (PE) approximation, yielding a 3D acoustic sensitivity field between

a source and a receiver. The acoustic sensitivity field is in fact connected to ocean

dynamics, and we can establish the connection using the chain rule of calculus. With

the sensitivity kernel technique, we can analyze the spatial distribution and the temporal

evolution of the acoustic sensitivity field in complex oceanic environments. The paper

will present numerical examples of 3D sound propagation in submarine canyons,

continental slopes and nonlinear internal wave fields. Discussions on other

applications of this sound pressure sensitivity kernel will also be provided, including

uncertainty quantification of transmission loss prediction and adjoint models for 3D

acoustic inversions.

28


29


Towards 3D Global Scale Underwater Sound Modeling

*Tiago Oliveira1, Ying-Tsong Lin2

*Presenter: [email protected] Marine Science Institute, National University of Singapore (NUS)

2 Applied Ocean Physics and Engineering Department, Woods Hole Oceanographic

Institution (WHOI), U.S.A.

ABSTRACT

Underwater low-frequency sound can travel great distances in the oceans, and it

can be detected at thousands of kilometers from the source. It is well known that a

variety of geological and physical oceanographic features can cause horizontal

refraction, reflection, and diffraction on global scale sound propagation. In this regard,

three-dimensional underwater sound models are required for accurately predicting

global scale sound propagation. However, solving accurately the long-range sound

propagation for fully 3D environments involves important scientific challenges and still

leads to very high computational costs.

In this work, we apply a 3D sound propagation model using the parabolic equation

(PE) approximation and the split-step Fourier (SSF) to model the sound field triggered

by a Southern Mid-Atlantic Ridge earthquake. As suggested by recorded field data, 3D

broadband simulations show a wide dispersion due to out-of-plane reflection/refraction.

Nevertheless, due to the lack of knowledge on the exact earthquake sound source

function, it becomes challenging to compare broadband model results with available

field data. In this regard, an adaptive back-propagation method will be evaluated for

recovering the source function. Based on the Southern Mid-Atlantic Ridge earthquake

case, a set of recommendations to improve 3D global scale underwater sound modeling

is presented.


Acoustic Propagation Effects of Subaqueous Sand Dune Bedforms in the South China Sea

*Linus Chiu1, Ching-Sang Chiu2, Chi-Fang Chen3, Yiing-Jian Yang3,

Ruey-Chang Wei1, Andrea Chang1

*Presenter: [email protected] National Sun Yat-sen University, Kaohsiung, Taiwan

2Naval Postgraduate School, Monterey, CA, USA 3 National Taiwan University, Taipei, Taiwan

ABSTRACT

In 2001－2010, the researches of ocean acoustics were focused on the effects of

watercolumn variability and smooth sloping bathymetry, and the resulting sound

propagation effects are known well. From 2012, interests are moved to the acoustic

effects induced by large-amplitude sand dunes. Moreover, large-amplitude sand dunes

and sand waves are discovered in the sea area around Taiwan, including the

northeastern South China Sea and the sea area off Taiwan. The amplitude and width of

sand dunes are much larger than acoustic wave length and will have significant impact

on sound propagation. This project is to study the acoustic propagation effects resulted

by various sand dunes. In this talk, international cooperated experiments were reviewed;

the experimental data of subaqueous sand dune field and the acoustic field and

numerical modeling were used to study the acoustic propagation effects. Channel

impulse response and the anisotropy of sound field were analyzed and discussed. [This

research was supported by the Ministry of Science and Technology of Taiwan with

project number MOST 104-2221-E-110-075 及 MOST 105-2221-E-110-050].

30


31


Challenges and Progress in the Study of the Effects of Noise on Marine Life

Douglas Herrod Cato

[email protected]

University of Sydney, Australia

ABSTRACT

The effects of noise of human activities on marine life have been studied for more

than 35 years and there has been substantial progress, but challenges remain for both

the research on noise impacts and the management of operations to minimise these

impacts. This paper will present an overview of the effects of noise on marine life and

management and mitigation procedures, and discuss the challenges remaining. Most of

the work has been directed at marine mammals, particularly whales, but there is

increasing interest in the effects of noise on fish and invertebrates. The paper will also

present some results of a major project on the response of humpback whales to the noise

of seismic air guns used in searching for oil and gas. It will also discuss the challenges

faced, how these were overcome by development of protocols that led to the successful

completion of the four major experiments. It will discuss and what was learnt that might

inform the design and conduct of future experiments on whale behaviour and other

marine animals in general. The project demonstrated the importance of ensuring that

research on the effects of noise on marine life is conducted by teams that include experts

in all the disciplines required, particularly underwater acoustics. It also demonstrated

the need for an adequate sample size of individual animals to be tested, since there is

significant variation among individuals of a species. There is also a need for the

experimental design to be a balance between trials in which the animals are exposed to

the noise source and control trials where there is no noise exposure. Without adequate

control trials, it is difficult to determine whether a behavioural response was due to the

noise exposure or something that the animals would have done anyway. Many previous

studies have fallen short in some or all of these.

32


Assessment of Noise Impacts on Marine Organisms

Tomonari Akamatsu

[email protected]

National Research Institute of Fisheries Science,

Fisheries Research and Education Agency, Japan

ABSTRACT

Underwater noise could cause behavioral, physiological and lethal impacts on

marine organisms. However, the responses are highly variable depends on the source

factors, sound propagation, sensitivity of animals, and background noise. By far, no

internationally recognized standard for the assessment of noise impacts is available

although national or regional level guidelines exist. Here key items for noise impact

assessment are listed for further discussion. Source factors such as source level,

frequency characteristics and directionality are possible to be measured, but in actual

case, reliable measurement is no easy. For example, the pile driving or shipping noise

are not point sources. Sound propagation especially in low frequency range at shallow

waters is a challenging theme. Not only oceanographic structure, but also precise

bathymetry and sediment conditions are required to solve sound propagation equations.

Acoustic sensitivity of small odontocetes are well understood but that of other taxa such

as baleen whales, fish and crustaceans are not extensively measured. Not only the sound

pressure, but also the sensitivity for the particle movement is hard to measure in situ.

Background noise level should be measured for long term at the potential impact zone.

Natural background noise level caused by soniferous animals are generally higher in

warm waters comparing with that in cold waters. Masking effect by the ambient noise

should be considered. At least the noise exposure level within the sensitive frequency

range of the animal should be higher when the potential noise impact is assumed.

Natural background noise changes depends on the time in a day, moon cycle and season,

too. Possible criteria for the noise regulation could be location and time dependent

based on extensive underwater sound monitoring at the impact zone. Note that

monitoring both at impact zone and control zone before during and after the

anthropogenic activates is the basic requirement for the impact assessment.

33


Silent Winters: Long Term Study of Fish Chorusing and Evidence of Impact of Continual

Shipping Noise on Fishes

*Siddagangaiah Shashidhar, Chi-Fang Chen


Underwater acoustic laboratory, Department of engineering sciences and ocean

engineering, National Taiwan University, R.O.C.

ABSTRACT

Recent deployment of Passive acoustic monitoring (PAM) autonomous recorders

off the Eastern Taiwan has resulted in collection of huge database of underwater

acoustic recordings from year 2014 to present. This has enabled us to quantify the

abundance, behavior, diversity and impact of noise on marine fauna. Here, we have

carried-out long term study of fish chorusing behavior at Changhua and Miaoli regions.

From past studies, it is known that fish chorus exhibit diurnal, nocturnal, seasonal and

lunar periodicity. However, these studies were restricted to short duration monitoring

without any clear species specific conclusion. Here, for the first time. We have shown

the changing behavior of the fish chorus over the varying season. The species of

croakers found at Changhua exhibit dawn and dusk chorusing from April-August, just

the dusk chorus from October-December, and maintain acoustic silence from January-

March. The region Miaoli was affected by continual shipping noise, due to which there

was ~10 dB rise in ambient noise levels and it is observed that these noise levels are

consistently increasing over the years. As a result, at Miaoli, there is a decrease in the

fish chorus intensity and also change in their chorusing pattern. This is the first clear

evidence of impact of long term shipping noise on the fishes.

34


Measurements of Pile Driving Noise from Offshore Wind Farm Construction in Southwest

Coast of Korea

*Dong-Gyun Han, Jee Woong Choi, and Jungyul Na


Hanyang university, Korea

ABSTRACT

The interest in wind power generation, as a kind of renewable energy, has been

increasing worldwide. Especially, offshore wind power generation has been developed

as an alternative to onshore windfarm, which is difficult to ensure the high-quality wind

resources and to resolve environmental problems such as landscape damage and

occurrence of noise. Impact pile driving is accompanied by the construction of wind

power generation and it produces an extremely high level of noise which may cause a

negative impact on marine ecosystem, especially, fishes and marine mammals. Thus, it

is important to monitor the noise level of the pile driving noise and to investigate its

propagation characteristics. Underwater noise generated from impact pile driving was

measured as a function of range in the southwest coast of Korea in 2017 and 2018. In

this talk, the measured noise levels will be presented and compared to the modelling

results. The propagation modelling of the impact pile driving noise is carried out using

the range dependent acoustic model (RAM) based on parabolic equation.


Calculating Marine Mammal Harassment Zones from Hydroacoustic Measurements and

Modeling of Pile Driving Operations

*Roberto Racca, Graham Warner, Alexander MacGillivray, Jorge Quijano,

Melanie Austin


JASCO Applied Sciences, Canada

ABSTRACT

Pile driving generates underwater sound at levels that can harass marine mammals

through disturbance and auditory injury. Environmental agencies in many national

governments have adopted criteria of varying complexity to define and estimate

potential for harassment. In 2016, The United States National Marine Fisheries Service

(NMFS) introduced new guidance for assessing potential of noise-induced injury,

moving from thresholds based on sound pressure levels to dual criteria considering both

peak pressure and cumulative sound exposure threshold levels specific to marine

mammal functional hearing groups. Because of the complexity of calculating

harassment zones using the full acoustic estimation framework of the new criteria,

NMFS provides a spreadsheet calculator, with simplified assumptions, that may be used

optionally to approximate the distances at which the impact thresholds are exceeded for

a given activity. This paper discusses, through case studies from operations in Southeast

Alaska, the implications of using three different approaches to estimate the distances to

both the new and old injury criteria and the (unchanged) SPL-based disturbance criteria

for vibratory driving and impact hammering cylindrical piles. In the first approach,

threshold distances were obtained using empirical regressions of sound levels measured

by seabed-mounted recorders at 10 and 1000 m nominal range. In the second, the

distances were obtained using the NMFS spreadsheet calculator. In the third, a finite-

difference pile driving source model was combined with a parabolic equation

propagation model to estimate received levels and distances to the marine mammal

harassment thresholds using the full framework of the NMFS guidance. The

comprehensive modeling foundation of the latter approach enabled to account for the

influence of environmental parameters such as sediment geoacoustics and bathymetric

features on the acoustic footprint of the operation, leading to a substantially closer

match with reference measurements.

35


36


Soundscape in Shallow Water of Dongsha Island, South China Sea

*Pai-Ho Chiu 1, Ruey-Chang Wei 1, Hin-Kiu Mok 1,2, Keryea Soong 2

*Presenter: [email protected] Institute of Undersea Technology, National Sun Yat-sen University, Taiwan

2 Department of Oceanography, National Sun Yat-sen University, Taiwan

ABSTRACT

Soundscape includes all sounds in one landscape, and it is the acoustic description

of a specific environment. Through long-term soundscape monitoring, interactions

between the living organisms and the environment can be more understood. Dongsha

Island is located within the Dongsha Atoll in the South China Sea and is an important

nursery habitat for many fishes and marine invertebrates. Underwater soundscape may

be a cue for larvae and juveniles of species living in the ecosystem to find the way in

the waters around Dongsha Island. To understand the underwater acoustic

characteristics of Dongsha Island, a suitable amount of related environmental and

biological data is needed. In this study, AUSOMS-mini was used to record underwater

sounds from two shallow-water sites (coral restoration area and shipwreck) on Dongsha

Island. According to the recordings, one peak around 3 kHz was observed at coral

restoration area. It seems that the sound pressure level (SPL) varied with tidal period.

It is speculated that certain activity of animals associated with tide emitted this

characteristic frequency. At the shipwreck site, SPL appeared higher than coral

restoration area as at least 15 dB at 1.6 kHz, 3 kHz and 5 kHz with low variation. It is

assumed that snapping shrimps or soniferous fishes made the frequencies as acoustic

characteristics.

37


Changes to the Fine-scale Habitat Use in Indo-Pacific Humpback Dolphins in Relation to

Vessel Traffic in Hong Kong SAR

*Matthew Pine1*, Ding Wang2, Lindsay Porter3, Francis Juanes1 Kexiong Wang2


1Department of Biology, University of Victoria, Victoria, British Columbia, Canada 2 Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China

3Sea Mammal Research Unit Hong Kong, St Andrews University, Hong Kong

ABSTRACT

Marine mammals depend on underwater sound for critical life processes. Those

processes include, but not limited to, keeping group members together while navigating

turbid waters, communication between family members, locating prey during feeding

and to avoid predators/danger. Their ability to communicate and sense their

environment using sound is therefore linked to the ambient sound environment;

whereby the biologically-important signal must be audible over the background sound

level. Developments within the Pearl River Estuary (PRE) (such as the HKIA Third

Runway Project, the HK-Macau-Zhuhai Bridge construction and Guishan offshore

wind farm construction) are causing ambient sound levels to rise – to the point where

communication between marine mammals can be masked and causing stress. Noise

pollution can therefore degrade marine mammal habitats around Hong Kong (among

other factors) and survey data between 2011 and 2016 shows that Indo-Pacific

humpback dolphins have moved to southwest Lantau waters and the Soko Islands, away

from the construction activity near their previous core-habitat north of Lantau Island.

However, the waters of SW Lantau Island have a high-degree of marine traffic,

particularly high-speed ferries and fishing vessels. The two primary risks to the

dolphins are auditory masking (potentially leading to reduced feeding efficiency) and

dolphin-vessel collisions (leading to serious injury and death). To investigate this risk,

passive acoustic monitoring from seven listening stations around SW Lantau Island and

the Soko Islands was undertaken between October 2016 and September 2017. Over the

calendar year, 4533 marine mammal detections revealed diurnal and seasonal changes

in the dolphins’ habitat use around the area. Changes in foraging behaviours appeared

to follow that of fish choruses, with no correlation to changing presence of vessel traffic.

These data provide valuable insights into how the fine-scale habitat use by dolphins

overlaps with vessel traffic, providing real data that will be used to formulate

conservation plans.

38

POSTERS

Part III

39


Yeon-Seong Choo, Sung-Hoon Byun, Sea-Moon Kim and Keunhwa Lee. Observation of Acoustic Echoes from Aluminum Hollow Sphere Using a Horizontal Line Array.

OBSERVATION OF ACOUSTIC ECHOES FROM ALUMINUM HOLLOW SPHERE USING A HORIZONTAL LINE ARRAY

Yeon-Seong Choo1, Sung-Hoon Byun2, Sea-Moon Kim2 ,and Keunhwa Lee3

1University of Science & Technology (UST) 2Korea Research Institute of Ships & Ocean Engineering (KRISO)3Department of Defense Systems Engineering, Sejong University

1. IntroductionThe features of acoustic scattering from elastic shells can be

an important clue for discrimination between man-made objectsand natural ones. The physics of such features has been studiedtheoretically by several researchers[1-2] and shown to bedetectable using low- or mid-frequency sonars[3].

This study presents the experimental results of observing theacoustic scattering characteristics from an aluminum hollowsphere. We tried to measure the difference when the inside ofthe sphere is filled with air or filled with water using the uniformlinear array with bistatic configuration.

3. Experiment & Signal processing

(a) (b)

(c)

Fig. 2. The experiment setup. Theexperiment was carried out in anopen water tank of 35x20x8m. Thedistance between target with thearray is 2m. (a) Front view, (b) Topview, (c) The photo

Fig. 4. Near-field beamformingsonar images. They show thedifferent scattered strengthaccording to target conditions(a) Water-filled target , (b) Air-filled target, (c) Non-target.

(a) (b)

(c)

Fig. 3. Normalized amplitude of scattered signal vs. frequency and comparison with the elastic shell scattering model of Hickling.

4. Conclusion & DiscussionAcoustic scattering of an aluminum sphere was observed with

the bistatic configuration at frequencies between 1 to 10 kHz. Theresults show that the beamformed image of the sphere isdependent on the fluid inside the sphere and also on the ratio ofacoustic wavelength to the size of the sphere. The peak locationsof the measured scattering signal level show some similaritieswith the theoretical model over 4 kHz (Fig. 3) but the limitedfrequency resolution of the probe signal makes it difficult toevaluate quantitatively. Below 4 kHz, it shows large deviationwith the model which is believed to be caused by the lowtransmit response of the acoustic projector used in theexperiment. We are going to do an additional experiment usingdifferent signals of better frequency resolution and also to applythe time-frequency analysis method for high resolutionlocalization of the scattered signals.

1. R. HICKLING, of echoes from a hollow metallic sphere inwater J. Acoust. Soc. Am., 36, pp.1124-1137 (1964).

2. K. J. DIERCKS and R. HICKLING, from hollow aluminumspheres in water J. Acoust. Soc. Am., 41, pp.380-393 (1967).

3. S. D. Anderson, K. G. Sabra, M. E. Zakharia, and J. Sessarego, -frequency analysis of the bistatic acoustic scattering from a sphericalelastic J. Acoust. Soc. Am., 131, pp.164-173 (2012).

5. Reference

PRUAC 2018 Email : [email protected]

Parameter ValueFrequency 1:0.25:10 kHz

Pulse Length 1msTarget Outer Radius 205mm

Target Thickness 20mmTarget Type Water-filled / Air-filled

2. TheoryAcoustic signals scattered from an elastic shell include the

specular wave scattered from outside of the shell as well as thecircumferential wave which are generated by Lamb wave.Therefore, the scattered signal is varied according to thediameter and the shell thickness of the sphere, and also the fluidproperty inside the sphere.

The acoustic scattering signals were measured from thealuminum sphere filled with water or air. Table 1 shows theprobe signal and target parameters of the experiment. Fig. 3shows the measured scattering signal level for different sphereconditions and compares them with the theoretical modelsuggested by Hickling [1]. As shown in Ref. [2], the soundscattering signals of a water-filled target was shown to havelarger scattering strength than an air-filled target below 10 ka(normalized frequency).

This research was supported by the Endowment Project of Korea Research Institute of Ships and Ocean engineering (PES9410).

Fig. 1. The configuration of acoustic scattering.

Table 1.

40


Cheng Jiang, Wen Xu, Jianlong Li and Zhongyue Chen. Temporal-Spatial Aggregation in Underwater Acoustic Passive Detection with A Mobile Node.

The bigger pitch angle, the betterperformance, because there areless spatial coherence along thevertical direction[2][3];When the pitch angle equals to ,the mobile node has the sameperformance as the static node.

• ;• Hz;• Only the numerical results are displayed

in the figure.

More measurements (longer accumulative time) can have a better performance.

• mobile node motions with a pitch angle of ;

• ;• Hz;• Only the numerical results are displayed

in the figure.

Temporal-Spatial Aggregation in Underwater AcousticPassive Detection with A Mobile Node

Cheng Jiang, Wen Xu*, Jianlong Li, and Zhongyue ChenCollege of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, 310027, China

Key Laboratory of Ocean Observation-Imaging Testbed of Zhejiang Province, Zhoushan, 316021, China*Email: [email protected]

Passive acoustic detection becomes a challenging problem due to both range- anddepth-dependent transmission loss in the ocean environment. This project proposesa passive target detection method that can be used on a mobile node equipped withsingle hydrophone. Simulation results show that in some scenarios, the proposedmethod outperforms the time accumulation accomplished by only a static node.

INTRODUCTION

Consider a binary hypothesis test problem. Let denote the hypothesis that onlyambient noise is received; and denote the hypothesis that a target presents.Hence, the problem can be modeled as

MODELING

And the detecting probability is

where is a vector with elements of 1. is the distribution function. Thedetail of the calculation process can be found in reference [1].For simulation comparison, we define the detecting probability of a two-dimensional region as

SIMULATION RESULTA square area with a length of 6000 meters;

Monte Carlo Runs;An unknown static target appears randomly in the square area with uniformdistribution and 50 meters depth for each Monte Carlo run;The static node locates in the central of the area at 30 m depth, mobile nodestarts motion from the central at 30 m depth in each Monte Carlo run, bothnodes have the same number of measurements;The velocity of mobile node is 0.35 m/sOne measurement per second;Ambient noise at 300 Hz is 57 dB, 1000 Hz is 54 dB;The source level of unknown static target ranges from 104 to 120 dB indifferent Monte Carlo run;Depth of the sea is 93 meters

In 1000 Hz case, mobile nodeoutperforms the static node,because there are more modes inhigh-frequency case;In 300 Hz case, both nodes havesimilar performance.

• Mobile node motions with a pitch angle of ;

• ;• Both nodes have 20 measurements;• Both Monte Carlo (MC) results and

numerical integration (N) results are displayed in the figure;


• ;• Both nodes have 20 measurements;• Depth of the sea is 1500 meters;• Only the numerical results are displayed

in the figure.


• Both nodes have 20 measurements;• Hz;• Only the numerical results are

displayed in the figure.

The mobile node has betterROC performance in bothsource level whenHz;The higher source level, thebetter performance.

[1] Moschopoulos, P. G., & Canada, W. B. (1984). The distribution function of a linear combination of chi-squares. Computers & Mathematics with Applications, 10(4), 383-386.[2] Lianghao, G., Zaixiao, G., & Lixin, W. (2001). Space and time coherence of acoustic field in shallow water. Chinese Physics Letters, 18(10), 1366.[3]Yang, T. C. (2012). Properties of underwater acoustic communication channels in shallow water. Journal of the Acoustical Society of America, 131(1), 129.

REFERENCES

CONCLUSION

In this project, we proposed a passive target detection method using a mobile node.Simulation results show that the proposed method outperforms the approach with a static node in some scenarios, especially when the unknown target source is a high frequency source.

Different from low-frequencyshallow water case, mobile nodeachieves better performance indeep water when dB at300 Hz;

where and is the number of measurements. is the receivedsignal. For a given frequency , the target signal and the ambient noise

are zero-mean Gaussian noises with variance and , respectively.denotes the transmission function which is determined by static target location

, receiver (mobile node) location , signal frequency and the environment.The energy detector is used in the mobile node, which can accumulate the energyof received signal. The equation is

where the is the detection threshold which can be calculated in CFAR case. Ifexceeds , decides ; else, decides .For a mobile node at given frequency , is a linear combination ofindependent central chi-squares variable with different weight

41


Donghyeon Kim, Yonghwa Choi, Gihoon Byun, Seongil Cho and Jeasoo Kim, Direction Finding of Snapping Shrimp Based on Δf - k Spectrum.

Direction finding of snapping shrimp based on spectrum

Frequency -wavenumber analysis can be used to estimate the direction of arrival (DOA) [J. Acoust. Soc. Am., 69, 732-737 (1980)]. When the receiver is a sparse array that is not suitable for conventional plane-wave beamforming, it adversely causes aliasing error due to spatial sampling, thus many striation patterns can emerge in domain. In this study, we propose difference frequency -wavenumber

analysis that is motivated by the frequency-difference beamforming [J. Acoust. Soc. Am., 132, 3018-3029 (2012)]. It is found that this approach can mitigate (or eliminate) such aliasing effect, which extends its applicability to the robust DOA estimation. Numerical simulation and experimental results are presented, and a major drawback is discussed. For experimental verification, the proposed algorithm was applied to the snapping shrimp noise observed during SAVEX15 experiment.

Donghyeon Kim1, Yonghwa Choi1, Gihoon Byun2, Seongil Cho3, and Jeasoo Kim1

1Korea Maritime and Ocean University (KMOU),2Scripps Institution of Oceanography (SIO),3Agency for Defense Development (ADD)

• During SAVEX15, a large number of unintended snapping shrimp noise were recorded by the receiving system.• Because the snapping shrimp noise is an impulse signal and the array is too sparse, the angle of snapping shrimp noise can’t be estimated.• We proposed the modified frequency wavenumber spectrum, that is difference frequency-wavenumber spectrum.• By comparing with the results of frequency-difference beamforming, the proposed algorithm was verified.

Abstract

SAVEX15

Song et al., “Underwater sound channel in the northeastern East China Sea,” Ocean

Engineering 147, 370-374 (2017)

Shallow-water Acoustic Variability EXperiment 2015 (SAVEX15)

Raw data (Snapping shrimp signal, SAVEX15)

1494 m/s

VLA

100m

Source (Snapping shrimp)

…

# 1 (23.5 m)

# 16 (79.8 m)

VL

1508 m/s

Spectrogram (# of ch : 8)

47.13 s – 47.18 s

JD15146165100

(dB)(dB)

Conventional beamforming output

Frequency-difference beamforming output

Frequency-difference beamforming output

(Incoherent sum)(Incoherent sum)

(dB)

(dB)

Conventional beamforming output(dB

(dB

Beamforming results (Conventional vs. Frequency-difference method)

Formula derived through frequency-difference beamforming

Frequency-difference beamforming

Frequency-difference component

Difference frequency-wavenumber spectrum

Frequency-difference

beamforming

Difference frequency –

wavenumber spectrum

FFT in spatial domain

spectrum

Data, Spectrum output (Snapping shrimp signal, SAVEX15)

spectrum

spectrum

47.13 s – 47.18 s

(dB)

(dB)

(dB)

Comparison : spectrum vs. Frequency-difference beamforming

(dB) (dB)

spectrum Frequency-difference beamforming

Data analysis

Conclusion

42


Sehyun Lee, Keunhwa Lee, Jun-Seok Lim, Myoung-Jun Cheong. Waveform Design for Compressive Sensing Active SONAR.

Waveform Design for Compressive Sensing Active SONAR

1Sehyun Lee, 1Keunhwa Lee, 2Jun-Seok Lim, 3Myoung-Jun Cheong 1Defense Systems Engineering, Sejong University, 2Electronic Information Communication Engineering, Sejong University,

3Agency for Defense Development, Korea

[1] Jindong Zhang, Adaptive Compressed Sensing Radar Oriented Toward Cognitive Detection in Dynamic Sparse Target Scene , IEEE Transactions on Signal Processing [2] Tao Hong, An efficient algorithm for designing projection matrix in compressive sensing

based on alternating optimization Signal Processing Volume 125, August 2016 [3] HAO HE, “Waveform design for active sensing systems-A computational approach”,

University of FLORIDA

Introduction

CS Active SONAR

Results

Conclusion

References

E-mails : [email protected]; [email protected]

2018 The 6th PAIFIC RIM UNDERWATER ACOUSTIC CONFERENCE Taipei/Hualien, Taiwan

Sept 2-5, 2018

Transmission Waveform Optimization

•

Fig 2. The range-Doppler plane of the target scene

•

Fig 3. The result of waveform optimization

Fig 4. Comparison of performances(Hit rate)

•

•

AF of LFM, N=100 AF of Optimized(L), N=100

43


Wei-Lun Li, Wei-Yen Chu and Chi-Fang Chen. Dolphin Whistle Detection.

Dolphin Whistle DetectionWei- Lun Li1 ,Wei-Yen Chu1 ,Chi-Fang Chen2

1Master student, Department of engineering Science and Ocean Engineering, National Taiwan University2Professor, Department of engineering Science and Ocean Engineering, National Taiwan University

IntroductionIn the past, research group of marine mammals employed localfishing vessel to approach the activities hot zone of whitedolphins and use the naked eyes to record the appearances ofdolphins. However, this approach is often restricted from theweather and night. To overcome these obstacles, the ultimategoal of this research is to establish an automated monitoringsystem. The PAM (passive acoustic monitoring) system provides asuitable way by placing the underwater recorder SM3M at fiveunder water acoustic station (P1-P5) to record dolphin’s whistle.

2017/04/25-05/18

Methodology

Smoothing

Denoising

Classification

Identification

Smooth Spectrum

• Envelope mean

Remove isolated noise

• Median-Filter

• Band width < 300Hz

• High Continuity in time domain

Automated classification

• Calculate the number ofwhistles.

• Use K-means to classifywhistles.

Result

Detection Ability

• Low False Alarm : 2-8%• Detect various type of whistles• High Accuracy : 90-94%

Constant Frequency

Sine wave & Up sampling

U-Type

Spatiotemporal continuity2017/05/04/16-17

2017/05/04/18-18:30

2017/05/04/18:30-19

2017/05/04/19• Pink color indicates that the dolphins have been

seen in the area.

• Detection range is computed by ASORPS.

• Blue color shows that the dolphins may be in this area

Localization Ability

Design of experiment

• Survey line : triangular, each side is 4km.• Use man-made sound source : chirp signal from 5 to 9 kHz

Use whistle detector to find the chirp signal& compute the correlation coefficient ofcomponents between different recorders.

• Localization median error=50m

• Localization Standard error=44m

Conclusion• We put Whistle-detector into the

practical applications, theexperiments to localize soundsource were done near theKaohsiung Harbor, the average ofthe positioning errors was 50 m.

• Whistle detector can be appliedinto the bio-sound detection &localization.

• The detection range in Miaoli is approximately 1.6~2.2km, because the transmission loss and source level of ambient noise must be considered.

Acknowledgements

Taipei/ Hualien, Taiwan , September 2-5,2018

44


Jingyao Liang, Ting Zhang, Wen Xu. Passive Localization Based on Distributed Network via Double-Correlation Function of Opportunity Sources.

Passive Localization Based on Distributed Networkvia Double-Correlation Function of Opportunity Sources

Jingyao Liang, Ting Zhang, Wen Xu*.College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou, 310027, China

Key Laboratory of Ocean Observation-Imaging Testbed of Zhejiang Province, Zhoushan, 316021, China*Email: [email protected]

Double-Correlation Function (DCF) of opportunity sources was first proposed byVerlinden[1] for passive source localization to effectively avoid precise modeling inclassical Matched Field Processing (MFP). Two times correlation have been donebetween sound field of the known source and that of the unknown one, which isactually a generalized MFP. This method in our work is extended into the distributednetwork application, with spatial gain greatly improved. Several kinds of topologicalnetwork are discussed through grating lobe structure and optimal detection range.

DCF via measured data avoids sound field modeling and shows stable localiza-tion performance. Distributed network also provides excellent spatial gain whichcould compensates bandwidth gain. Over three topological structures above, thesquare array has best performance and is suitable for the detection of the target atmoderate distance.

When receiver 1 and 2 are at the same position, is equal to one.

Variable definition• : the field

received at j, emitted from source i atfrequency .

• distance between source i and receiverj, and .

• underwater sound speed.

DCF is intrinsically the beamforming of 2 nodes, so the beampattern at eachfrequency appears different. The higher the frequency is, the more grating lobes thereare.

The grating lobes could be attenuated by averaging over several frequencies,nevertheless, there still exists difficulties when the overlap between known andunknown signal spectrum is not sufficient enough. Distributed network provides aspatial gain which compensates the poor bandwidth gain.

Double-Correlation Function

Averaging over all frequency components of DCF derived from broadband data,the grating lobes (or the side lobes) will be reduced, while the main peak will bereserved and amplified. The localization result is ameliorated with a growth numberof frequencies taken in averaging.

θ=60

4km

4km

2 receivers anchored at bottom

10m

1km

Detected area

Simulation parameters are the same as in reference [1]. Assembling DCF at everygrid generates the ambiguous function of localization.

Three Topological Structures

1km

1km1.5km

The last row of every figure is thenetwork beampattern and others arebeampatterns of every two adjacentnodes.

The square array induces leastgrating lobes at single frequency owingto the diversity of spatial distributionand spatial sampling frequencies.

1km

(a) ULA (b) NULA

(c) Square array

Optimal Detection Range

• Short distance: Uniform lobes, no main lobe appears.• Moderate distance: Dominant main lobes begin to appear even at single

frequency.• Long distance: Similar to plane wave case.

The optimal detection range is about 6-8 kilometers in this configuration.

Network beampattern depends on the distance between source and nodes, wherethe point source and wide area network cause the failure of plane wave hypothesis.

[1] Verlinden, C. (2014). Passive Acoustic Techniques Using Sources of Opportunity (Doctoral dissertation, UC San Diego).[2] Verlinden, C. M. (2017). Acoustic sources of opportunity in the marine environment-Applied to source localization and ocean sensing. University of California, San Diego.

Receivera

b

Source 1 2

Measured data

1st correlation

2nd correlation

nbn

gta

m

) array

45


Kuan-Wen Liu and Ching-Jer Huang. Real-time Monitoring of Underwater Sound Using a Buoy Installed with a Hydrophone.

III. Data Analysis Method• Fast Fourier Transform (FFT)

In this study, FFT is applied to convert data fromthe time domain to the frequency domain to obtainfrequency characteristics.• Sound pressure level (SPL)

The method of underwater energy quantification issimilar to the method for calculating the SPL in theair.

where SPL is presented in decibel (dB); is themeasured sound pressure; is the reference soundpressure, which is 10 in water.

• Relation of wave height change – SPL changeOnce the relation between SPL and wave height was

established, the variation in wave height and SPL couldalso be determined for each frequency. In right figure, itis easy to determine the SPL change from the waveheight change once the frequency of interest wasconfirmed. From this figure, the increase of SPL withthe wave height is frequency dependent. Therefore,once the wave height was known, the underwater SPLcould be obtained.

SPL

chan

ge, d

B

Wave height change, cm

SPL,

dB

re 1

Pa

Frequency, Hz

V. Conclusions1. The results of this study show that there was a

relation between SPL and wave height, based onthe analysis of the waves and ambient noisesmonitoring data.

2. SPL increased with an increase in the wave heightfrom 20 to 120 cm.

3. Our monitoring results showed that the increase ofSPL with the wave height is frequency dependent.

II. Experimental Set-up• System integration

The underwater sound monitoring system includeda hydrophone, data logger, computer, and a 4Gnetwork. The data logger used the hydrophone as asound pressure sensor to control the data acquisitionfor three minutes every hour. The data were saved ina computer’s memory card and were calculated aftereach data acquisition. The analyzed data was sent toanother computer through a 4G network.• Installation

A buoy was used as a carrier for the underwatersound monitoring system, a wave height meter, and apower supply in the form of solar panels and batteriesfor all the equipment. The hydrophone with apreamplifier was installed on the buoy about 1 meterbelow the sea surface. The wave height meter wasinstalled at the same height as the water surface. Therest of the equipment, such as batteries, computer,and data logger, among others, are in the hull.• Detection progress

In the normal mode, the data logger stayed asleepbefore warming up, which was two minutes beforethe start of data acquisition every hour, to conservethe battery power. In this mode, the system couldsurvive for months. Furthermore, the event modecould be switched on as needed. The acquisition timecould be then modified remotely.

Real-time monitoring of underwater sound using a buoy installed with a hydrophoneKuan-Wen Liu Ching-Jer Huang

National Cheng Kung UniversityAbstract

This research aims to develop a cost-effectiveunderwater sound monitor to obtain long-term andreal-time underwater ambient noise and its spectrum.The results of this research indicate that a relationbetween wave height and sound pressure level (SPL)was found near the southwestern coast of Taiwan.

IV. Results & Discussions• Relation of SPL – Wave height

Since November 2015, a buoy with real-timeunderwater sound monitoring system was deployed inthe southwestern coast of Taiwan, with a water depth of18 meters. Each sound pressure signal data was firstanalyzed through FFT and then converted to SPL.Then, they were sorted by the wave height to observethe relation between SPL and wave height. It is evidentthat the SPL increased as the function of wave heightonly up to 200 Hz. The more data of wave height, themore phenomena could be observed and discussed.

Shut down

Warming up

Acquire & Save

Send back

2 minutes 3 minutes

Data buoy during deployment

Raspberry pias computer

TermUB as data loggerwith 32GB memory

HTI-94-SSQ as hydrophone

= 10log PI. Introduction

The underwater sound monitor included severalequipment and can be deployed on a buoy. The datacan be used for object detection and surveillance. Inthis research, a relation between wave height andSPL was found. Then, since the wave height meterswere widespread, the changes in wave height wereused to calculate the changes in SPL.

46


Raegeun Oh, Bon-Sung Gu, Taek-Lyul Song and Jee Woong Choi. Correction of Bearing Error of Line Array Sonar System Due to Bottom Bounced Path Signal.

Correction of bearing error of line array sonar system due to bottom bounced path signal

, , ,

Hanyang Univ., Republic of Korea Navy

47


Presenters Index

A Akamatsu, Tomonari [email protected] 32

C

Cato, Douglas [email protected] 31

Chapman, Ross [email protected] 12

Chiu, Ching-Sang [email protected] 27

Chiu, Linus [email protected] 30

Chiu, Pai-Ho [email protected] 36

D

Du, Shuyuan [email protected] 24

F

Feng, Chao [email protected] 20

H

Han, Dong-Gyun [email protected] 34

L

Li, Fenghua [email protected] 15

Li, Zhenglin [email protected] 23

Lin, Ying-Tsong [email protected] 28

M

Maksimov, A. O. [email protected] 26

Ma, Yuanliang [email protected] 14

O

Oliveira, Tiago [email protected] 29

P

Pine, Matthew [email protected] 37

Porter, Michael [email protected] 13

48


R

Racca, Roberto [email protected] 35

S

Siddagangaiah Shashidhar [email protected] 33

T

Too, Gee-Pinn James [email protected] 19

W

Wu, Fei-Yun [email protected] 25

X

Xu, Wen [email protected] 21

Y

Yang, T. C. [email protected] 17

Z

Zeng, Juan [email protected] 18

Zhang, Yan [email protected] 22

Zhao, Zhen Dong [email protected] 16

49


Conference Program

September 2 (Sunday)

13:30-14:00 Registration

14:00-16:00 Welcome IceBreaker – Cheer Hall, Cosmos Hotel Taipei

September 3 (Monday)

08:30-09:10 Opening Ceremony Chaired by Chi-Fang Chen

09:10-09:50 Plenary Lecture

Sounds in the Ocean: Experiments and Measurements in

Underwater Acoustics. Ross Norman Chapman

09:50-10:00 Group Photo

10:00-10:20 Coffee Break

10:20-12:00 Session 1 Chaired by Linus Y.S. Chiu

10:20-10:40

1-1 Fully 3D Sound Propagation in the Weymouth Fore River,

with a Dry-Dock and a Ship Hull. Michael Porter, Laurel

J. Henderson, John Peterson, Tim Duda, Arthur Newhall,

Peter Traykovski

10:40-11:00 1-2 Underwater Acoustic Sensor Array Processing: Problems

and Improving Approaches. Yuanliang Ma, Yixin Yang,

Yong Wang

11:00-11:20 1-3 Radial Velocity Estimation of Moving Source Using

Pressure Difference of Dual Hydrophones. Ruijie Meng,

Shihong Zhou, Fenghua Li

11:20-11:40 1-4 A Model-free Approach for Inverting the Intrinsic

Attenuationα(f) of Sea-bed Sediment. Zhen Dong Zhao, J.

Zeng, L. Ma, E. C. Shang

11:40-12:00 1-5 Deconvolved Conventional Beamforming Applied to the

SW06 and SWellEx96 data. T. C. Yang, S. H. Huang

12:00-13:30 Lunch

13:30-15:30 Session 2 Chaired by C. J. Huang

13:30-13:50 2-1 A Simple Estimation of the Seabed Sound Speed with the

Group Speed of the Critical Mode. Juan Zeng, Z.D. Zhao,

L. Ma, E. C. Shang

50


13:50-14:10 2-2 Comparison of Alternative Underwater Communication

Modulation Schemes in Various Conditions. Gee-Pinn

James Too, Lin-Hua Hsu, Kuan-Yuan Chen

14:10-14:30 2-3 An Effective System Modeling Method for the Reduction

of Low Frequency Noise from Marine Detection UUVs.

XiaoChuan Ma, Chao Feng

14:30-14:50 2-4 2016 Shallow-Water Experiment on Ocean Acoustic-

Dynamic Coupled Data Assimilation in South China Sea.

Wen Xu, Lianlong Li

14:50-15:10 2-5 A Range-estimation Method for Surface Sources Based

on the Characteristic of Bottom Bounced Sound in Deep

Water. Yan Zhang, Shihong Zhou


Session 3 Chaired by Gee-Pinn James Too

15:30-15:50 3-1 Sound Propagation in Deep Water with a Sloping Bottom.

Zhenglin Li, Renhe Zhang, Zhiguo Hu

15:50-16:10 3-2 Full Wavefield Computation and Propagation

Simulations in Typical Irregular Seabottom Environment.

Shuyuan Du, Shihong Zhou, Yubo Qi

16:10-16:30 3-3 An Improved Non-uniform Norm Method for Sparse

Channel Estimation. Fei-Yun Wu, Kun-de Yang, Rui Duan,

Hui Li

16:30-16:50 3-4 Bubble Dynamics Near an Interface. A.O. Maksimov, Yu

A. Polovinka

09:50-18:30 Poster Session Chaired by Andrea Y.Y. Chang

16:50-18:30 Speed Talk (poster)

18:30-21:00 Poster Award ceremony

Dinner Banquet

September 4 (Tuesday)

Session 4 Chaired by Chung-Wu Wang

08:30-08:50

4-1 Geoacoustic Properties of, and Propagation Anisotropy

Induced by, Subaqueous Sand Dunes on the Upper-slope

of the Northeastern South China Sea. Ching-Sang Chiu,

Linus Y. S. Chiu, Chi-Fang, Chen, Yiing Jang Yang, Jiann-

Yuh Lou, Christopher W. Miller

51


08:50-09:10 4-2 Underwater Sound Pressure Sensitivity in Three-

Dimensional Oceanic Environments. Ying-Tsong Lin

09:10-09:30 4-3 Towards 3D Global Scale Underwater Sound Modeling.

Tiago Oliveira, Ying-Tsong Lin

09:30-09:50 4-4 Acoustic Propagation Effects of Subaqueous Sand Dune

Bedforms in the South China Sea. Linus Chiu

10:00-18:00 Local Tour to Taroko National Park

18:00-21:00 Dinner

September 5 (Wednesday)

Plenary Speaker

08:30-09:10 Challenges and Progress in the Study of the Effects of Noise

on Marine Life. Douglas Cato

Session 5 Chaired by Ruey-Chang Wei

09:10-09:30 5-1 Assessment of Noise Impacts on Marine Organisms.

Tomonari Akamatsu

09:30-09:50 5-2 Silent Winters: Long Term Study of Fish Chorusing and

Evidence of Impact of Continual Shipping Noise on

Fishes. Siddagangaiah Shashidhar, Chi-Fang Chen

09:50-10:10 5-3 Measurements of Pile Driving Noise from Offshore Wind

Farm Construction in Southwest Coast of Korea. Dong-

Gyun Han, Jee Woong Choi, Jungyul Na


10:30-10:50

5-4 Calculating Marine Mammal Harassment Zones from

Hydroacoustic Measurements and Modelling of Pile

Driving Operations. Roberto Racca, Graham Warner,

Alexander MacGillivray, Jorge Quijano, Melanie Austin

10:50-11:10 5-5 Soundscape in Shallow Water of Dongsha Island, South

China Sea. Pai-Ho Chiu, Ruey-Chang Wei, Hin-Kiu Mok,

Keryea Soong

11:10-11:30

5-6 Changes to the Fine-scale Habitat Use in Indo-Pacific

Humpback Dolphins in Relation to Vessel Traffic in Hong

Kong SAR. Matthew Pine, Ding Wang, Lindsay Porter,

Francis Juanes, Kexiong Wang

11:30-12:00 Closing Ceremony Chaired by Chi-Fang Chen

Announcement of next PRUAC

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