Study on the effect of underwater noise on the behavior of dolphins

随着海洋经济的发展，民船航行、海洋资源勘探、港口建设、海洋科考等海上活动产生的水下噪声，给赖以声纳系统生存的海洋哺乳动物带来严重影响。这些影响已引起欧美发达国家的重视，并开展大量研究，美国于2013年颁布临时性标准，规定大多数海洋哺乳动物所可承受的脉冲型声压级应低于190dB（re1μPa）。而我国在这方面研究起步较晚，尚缺少水下噪声对海洋哺乳动物影响的评估标准和有效技术手段。 中华白海豚（Sousachinensis）作为我国特有的海洋哺乳动物，2008年，国际自然保护联盟濒危物种红色名录中将其列为“接近濒危”的物种。与其他海洋哺乳动物相比，国内外对中华白海豚的研究均较少，因此，如何有效评...Increased anthropogenic underwater noise from a variety of sources, including commercial ship, marine resources exploration, construction, acoustic research, etc, has seriously affected marine environment. The developed countries in Europe and America have increasingly concerned about the problem and carried out many studies. America issued a provisional standard in 2013, which regulated sound pre...学位：理学博士院系专业：海洋与地球学院_海洋物理学号：3112010015358

Embedded Underwater Acoustic Frequency-Hopping Communication Technologies Research Based on DSP

水声通信技术是当代海洋资源开发和国家安全保障的重要组成部分，也是我国海洋高技术急待研究开发的项目之一。随着现代海洋资源开发的迅猛发展和国家海洋安全的迫切需求，水声通信技术的研究越来越受到人们的重视。但是水声信道是一个十分复杂的时空频变随机多径信道，再加上高噪声、窄带宽、载波频率低、大起伏、传输时延大等特点，给水声通信带来极大的困难，其中强多径效应和大幅度起伏是造成水声通信性能较差的主要因素，它会导致信号幅度衰落和严重的码间干扰。 近年来实际应用的迫切需求，水声网络通信成为国际水声技术领域研究的热点课题。而在水声通信网络中，实现可靠、稳健的点对点物理通信是水声网络通信的前提。本论文选题正是在这...Underwater acoustic communication (UAC) Technology plays an important role in marine resource exploitation and national security etc. With the rapid development of marine resource exploitation and urgent demand of National Ocean security, UAC Technology has been paid more and more attention. However, underwater acoustic (UWA) channel is expressed as a complex channel which is randomly variable in ...学位：理学硕士院系专业：海洋与环境学院海洋学系_海洋物理学号：2112005130219

A Real-time Frequency-hopping Communication System in Underwater Acoustic Channel Based on DSP

水声信道是一种极其复杂的时空频变信道,在进行水声通信中,必须克服强多途和大起伏等干扰.抗干扰能力强、隐蔽性好的跳频通信技术应用于水声通信领域,具有独特的优势,是近年来高稳健性水声通信技术研究中的一个热点.本文构建了一种基于DSP硬件平台的实时水声跳频通信系统,给出了系统编解码技术的实现方法.发射的帧信号由粗同步信号、细同步信号、时延信号和m序列生成的跳频信号组成,采用补零FFT的方法进行解码,提高了鉴频分辨率.通过实验室水池实验,验证了所设计系统在低信噪比条件下的可行性和稳定性.由于m序列生成的跳频图案隐蔽性强,该系统也可用于水声保密通信.Underwater acoustic(UWA) channel is expressed as complex channel which is randomly variable in time-space-frequency.Combating the strong underwater multipath and large fluctuation is the most challenging task of an UWA communication system.Frequency-hopping(FH) communication system features its low probability of intercept and anti-interference which is widely applicated in underwater acoustic communication recently.A real-time FH communication system based on high-speed digital signal processor(DSP) was introduced in this paper.The frame of transition signal was composed of coarse and subtle synchronization,time delay signal and FH signal created by M-sequence.Fill zero FFT method was used to demodulate received signal and to improve the ability of frequency discrimination.The laboratory pool experimental results verified the good performances of the system in robustness and feasibility.国家自然科学基金(40776022);; 福建省科技重点项目(2006N0042)资

Corporate Governance and Firm Performance of Listed Firms in Sri Lanka

Conference Name:International Conference of the Asia-Pacific-Business-Innovation-and-Technology-Management-Society. Conference Address: Pattaya, THAILAND. Time:JAN 13-15, 2012.The aim of this study is to examine the relationship between corporate governance structures and firm performance of listed firms on Colombo Stock Exchange (CSE) in Sri Lanka. Data were collected from 174 firms in the financial year 2010 and multiple regression analysis were used to examine whether the existing corporate governance mechanisms influence the firm performance of listed firms in Sri Lanka. The study found evidence that, (i) board size and proportion of non-executive directors in the board shows a marginal negative relationship with firm value, (ii) proportion of non-executive directors in a board and financial performance of firm shows negative relation contrary to the findings of previous studies. The firm size and director shareholdings have a significant impact on firm performance of listed firms in Sri Lanka. (C) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Asia Pacific Business Innovation and Technology Management Societ

Comparison study on whistle characteristics of captive bottlenose dolphins(Tursiops truncatus) during swimming and under training

根据频率特性对圈养宽吻海豚(TurSIOPS TrunCATuS)在自由游动和训练两种实验条件下的声通讯信号进行分类,并利用双尾T检验统计分析方法对两种条件下的信号声谱参数进行统计比较。结果显示,宽吻海豚在自由状态下通讯信号的种类多并以正弦型为主,而训练期间的通讯信号则大多数为上扫频类。此外,统计分析表明起始频率不能反映这两种状态的不同(P=0.22)。结束频率、最小频率、最大频率、频率变化量、拐点数、环形数、阶数、波形数和周期等则显示了两种状态显著的差异性(P<0.05)。结果为今后海豚声行为研究提供一定的科学参考和基础。This study compared the whistles recorded from captive bottlenose dolphins(Tursiops truncatus) under two different experimental conditions(swimming and training) based on the signals' frequency characteristics,and the t-test was applied for statistical analysis.The results showed that most of the signals were the sine category when the dolphins were in swimming,however,they became the upsweep category when the dolphins were received training.Furthermore,the statistical analysis indicated that the beginning frequency might not reflect the significant difference between these two experimental conditions(p=0.22),however,the ending frequency,minimum frequency,maximum frequency,frequency variation,number of turns,number of loops,number of steps,number of waves,and duration all showed the significant differences between the two experimental conditions(p<0.05).The results may be valuable for further study on dolphin acoustics under different biological behaviors.国家自然科学基金(41276040;11174240); 海洋公益性行业科研专项(201105011-3); 福建省自然科学基金(2012J06010;2060203)资

Simulation study on the time-varying multipath model for underwater acoustic channel

本文针对浅海水声信道的时变特性,基于射线理论引入海洋参数———强度起伏参数Φ、不均匀度参数Λ,建立有效的时变多径信道模型,并采用MATlAb工具进行仿真.仿真结果表明,该模型相比于确定性模型更容易理解、更真实.文中给出的模型和结论能够为实际通信系统中发射接收机深度等的选择和设计提供一定的参考和依据,有助于对水声信道的了解.According to time-varying characters of underwater acoustic(UWA) channel,an effective model of time-varying multipath channel based on ray theory is developed.In the model,two important ocean parameters,the strength parameter Φ and the size parameter Λ,are introduced.Through computer simulation,the model provides more intelligible and realistic results than the deterministic model.The simulation results offer a certain reference and basis for analysis and design of the receiver depth,which is helpful for understanding the character of the UWA channel.国家海洋局第三海洋研究所基本科研业务费专项基金资助项目(2009049

A Method of Acoustic Transmission Loss Calculated with Background Noise Removal-energy Summation

利用常规声传播损失方法计算实测水声场信号时,发现在低信噪比下计算得到的声传播损失存在较大误差.因此,利用能量谱去噪声原理,改进了常规声传播损失的计算方法,并比较分析了2种方法的结果.研究结果表明:当海洋环境条件较复杂、不易区分干扰源时,或者在低信噪比下的远程水声传播中,采用改进的声传播损失计算方法能够较好地抑制噪声、有效地提取信号能量和提高信噪比.A method of background noise removal-energy summation was introduced in the paper to improve the estimable precision of acoustic transmission loss of measured signals.By using an old general FFT energy summation method to calculate the acoustic transmission,a lower detectable precision was found in measured long-range sound propagation signals.In order to improve the estimable precision,the paper come up with a modified method named background noise removal-energy summation to calculate acoustic signals based on the general FFT energy summation.Then,the result showed that the experimental transmission losses with the new method were agreed well with the model-simulated data.Therefore,the using of background noise removal-energy summation method in signal processing is more effective to extract the real signal energy and has the capacity of improving signal to noise ratio.福建省科技重点项目(2006N0042)资

Study on the Characteristics of Echolocation Clicks from Indo-Pacific Humpback Dolphins(Sousa chinensis) in Xiamen

对厦门海域中华白海豚的发声及信号特性进行研究,采用高频宽带数据记录系统获取了大量中华白海豚ClICk信号,并利用MATlAb软件和EXCEl 2007对这些信号进行时域和频域分析.结果表明:ClICk信号通常以不同长度的序列形式出现,单个ClICk信号长度分布在(33±4)μS;频谱能量分布广,低频至10kHz,高频达200kHz以上,具有单峰和双峰2种频谱结构,峰值频率、3db带宽和10db带宽分别为(113.3±16.3)、(48.3±14.2)和(113.3±16.4)kHz.中华白海豚ClICk信号双峰的频率分布,为其在海底混响严重的浅海环境准确识别目标提供了保障.The vocalizations and signal characteristics of humpback dolphins(Sousa chinensis) in Xiamen were studied in this paper.A large number of original click signals were obtained by a broad frequency-band recording system.These signals were analysed as waveforms and spectrograms using Matlab tool and Excel 2007.Results of this study indicate that clicks of humpback dolphins occur as trains.The duration of each click trains vary wildly,ranging from a few seconds to tens of seconds,but single click have a short duration around(33±4) μs.The echolocation clicks have a wide range of frequency distribution between 10 kHz and 200 kHz.Click signals have two types of spectrum structure and have an averaged peak frequency of(113.3±16.3) kHz with 3 dB bandwidth of(48.3±14.2) kHz.The 10 dB bandwidth of(113.3±16.4) kHz is also given in the results.Most of the echolocation clicks have a bimodal frequency distribution,which provides a good range resolution capability that should enable dolphins to be able to perform fine target discrimination in a shallow water environment where bottom reverberation can be troublesome.海洋公益性行业科研专项(201105011-3);中国博士后科学基金项目(2011M501082

Behavioral responses of captive bottlenose dolphins(Tursiops truncatus) to a continuous 20 kHz pure tone

将20 kHz连续声信号作为刺激信号,测试了厦门某海湾圈养的两只瓶鼻海豚对该信号的行为变化。通过对比信号发射期与间歇期海豚相对声源的水面距离、露出水面的次数以及水下发出的ClICk定位声信号的数目等变化,判断发射信号对海豚行为的影响。给出了瓶鼻海豚对测试信号产生躲避行为的声压级门限(154±2 db rE 1μPA,rMS),并与鼠海豚的躲避声压门限级进行了对比。结果表明:信号发射期,瓶鼻海豚移离了声源位置,增加了露出水面的次数,水下发出ClICk声信号的次数明显减少。因此,瓶鼻海豚对20kHz连续信号产生了行为改变。Two captive bottlenose dolphins housed in a float cage in a Bay were subjected to a continuous 20 kHz tonal signal.The behavioral responses of dolphins were judged by comparing the surface distances relative to the sound source,number of surfacings,and number of the echolocation clicks production of the dolphins,during test periods and baseline periods.The avoidance threshold sound pressure level(SPL)for a continuous 20 kHz tonal signal for the bottlenose dolphins was estimated to be 154±2 dB(re 1μPa,rms).In addation,the comparison between the avoidance threshold SPL for harbor porpoises to a 50 kHz continuous signal and bottlenose dolphins to a 20 kHz continuous signal was also studied.The results showed that the dolphins moved away from the sound source and came to the surface more frequently during the test periods than the baseline periods,but they produced clicks significantly fewer.Therefore,a continuous 20 kHz tonal signal seems to deter bottlenose dolphins from an area.国家海洋局青年科学基金(2010422);海洋公益性行业科研专项(201105011-3)项目;国家海洋局第三海洋研究所基本科研业务专项(海三科2009010)资

An automatic classification method for whistles of bottlenose dolphin(Tursiops truncates)

针对宽吻海豚通讯信号自动分类提出了一种基于句法模式识别的方法。该方法首先提取海豚通讯信号基频随时间变化的轨迹曲线,然后提取基频变化的基元序列。根据海豚通讯信号分类的标准,归纳出产生各类海豚通讯信号基频基元序列的文法。对未知类别的海豚通讯信号,提取其基频变化的基元序列,根据各类模式的文法对基元序列进行分类,进而实现海豚通讯信号的自动分类。实验结果显示本文方法的分类准确率达到了95%。本文方法预期为海豚生物学行为的声学研究提供一定的技术支持。To automatically classify bottlenose dolphin's whistles,a method,which is based on syntactic pattern recognition,is presented.Dolphin whistles have typically been characterized in terms of their instantaneous frequency as a function of time,which is also known as "whistle contour".The frequency variation feature of a dolphin whistle is extracted according to its whistle contour.Then,the frequency variation features are used for learning grammatical patterns.A dolphin whistle is classified according to grammatical pattern of its frequency variation feature.Experimental results show that the classification accuracy of the proposed method is 95%.The method can provide technical support for acoustic study of dolphins' biological behavior