The physical mechanism of beam formation in dolphin’s biosonar

作为群居的海洋哺乳动物，齿鲸类拥有着与众不同且功能强大的生物声呐系统。其生物声呐系统经过自然界的长期演化和优胜劣汰，性能已高度优化。海豚的回声定位声波能够在百米内探测到厘米级大小的物体，并对毫米级厚度的金属目标做出辨别，此外还能在探测移动目标的时候对其波束特性进行调整，其性能远远优于目前世界上任何的人工声呐。其生物声呐系统卓越的性能引起了世界上声学研究者强烈的兴趣，不但使得齿鲸类生物声呐研究成为近年来生物声学界以及国际海洋声学界的焦点，还成为新型海洋技术开发值得关注的高新科技领域，对海洋珍稀哺乳动物种类的保护和发展仿生声纳技术具有极其重要意义。但由于生物声纳的研究属于声学、生物学、仿生学等交叉...As gregarious marine mammals, odontocetes have sophisticated biosonar systems. The evolutionary process has led to a highly optimization on their biosonar systems. An echolocating dolphin can detect centimeter level object more than one hundred meters away and can also distinguish a metal object with its thickness at millimeter level. Additionally, they can adjust their biosonar beam when they are...学位：理学博士院系专业：海洋与地球学院_海洋物理学号：3112011015361

Study on the Classification of Dolphin’s Whistle and the Acoustic Protection

海豚是一种群居的海洋哺乳动物，与其他大部分的动物不同，它们依靠强大的声纳系统与外界沟通，通过收发声信号来觅食、玩耍、躲避天敌、相互交流合作、抒发情感等等。海豚的听觉频域为150Hz~280kHz，发声频域为120Hz~300kHz，对声音极其敏感，能分辨出200Hz~130kHz范围内0.2%~0.8%的频率变化。而海豚所生活的水域恰好与人类海上经济活动海域相重叠。随着近年来海洋资源的开发利用以及海洋经济的迅速发展，人类活动对海洋生态环境和海洋生物资源造成严重影响，尤其是水下爆破、海底打桩、潜艇声纳、船只航运等等所产生的噪声将严重干扰到海豚赖以生存的声纳系统，使海豚长期处在一种焦躁烦闷、惊恐不...Dolphins are a kind of gregarious marine mammals, they distinguish themselves form other animals in their strong sonar system by which they communicate with each other. They use the acoustic signal to forage, play, avoid predators, cooperate, express emotions, etc. The hearing frequency range of a dolphin is about 150Hz~280kHz and the vocalization frequency range is about 120Hz~300kHz. They are ex...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：3112008115145

Synthesized acoustic signal characteristics of net-cage-cultured Large Yellow Croaker,Pseudosciaena crocea

对所采集到网箱中人工养殖的两组不同年龄大黄鱼(PSEudOSCIAEnA CrOCEA)产生的声信号进行定量分析和比较,运用分段指数振荡函数合成大黄鱼声信号,并利用振荡频率和衰减指数定量地描述了鱼声信号特性。结果显示,合成的大黄鱼声信号在时频域都显示出很好的拟合优度,13—15月鱼龄组的平均振荡频率和衰减指数均低于7—8月鱼龄组。结果表明函数的振荡频率和衰减指数与大黄鱼发声的物理过程及年龄特征存在一定的联系,为今后人工养殖大黄鱼中声学技术的相关应用提供一定的科学参考和基础。This study performs the quantitative analysis and comparison to acoustic signal characteristics of Large Yellow Croaker(Pseudosciaena crocea) at two different ages.The sounds were recorded from the fishes in a net-cage.Two exponential oscillation functions are built to fit the acoustic signal of the fishes.The signal characteristic of the oscillation frequency and attenuation coefficient was described quantitatively.Simulation curves of the function could fit well acoustic signals.Both the average oscillation frequency and attenuation coefficient of the fitted signals from the 13-15-month-old fishes are lower than those from the 7-8-month-old fishes.The results suggest that the oscillation frequency and attenuation coefficient of the acoustic signal function may be relevant to the physical process of sound production and age characteristics of Large Yellow Croaker.This study may be valuable for the acoustic application to the artificial culture of the species.国家自然科学基金(11174240); 福建省自然科学基金(2060203)计划资助项

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

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

94MeV Xe离子辐照引起的薄膜硅光学带隙变化研究；Modification of Optical Bandgap of Thin Silicon Films Induced by 94 MeV Xe Ion Irradiation

室温下,用94MeV的Xe离子辐照纳米晶和非晶硅薄膜以及单晶硅样品,辐照量分别为1.0×1011,1.0×1012和1.0×1013ions/cm2。所有样品均在室温下用UV/VIS/NIR光谱仪进行检测分析。通过对比研究了纳米晶、非晶、单晶硅样品的光学带隙随Xe离子辐照量的变化。结果表明,不同结构的硅材料中Xe离子辐照引起的光学带隙变化规律差异显著:随着Xe离子辐照量的增加,单晶硅的光学带隙基本不变,非晶硅薄膜的光学带隙由初始的约1.78eV逐渐减小到约1.54eV,而纳米晶硅薄膜的光学带隙则由初始的约1.50eV快速增大至约1.81eV,然后再减小至约1.67eV。对硅材料结构影响辐照效应的机理进行了初步探讨