On electro-acoustic characteristics of a marine broadband sparker for seismic exploration

The construction of major marine infrastructure projects and the exploration and development of deep-sea mineral resources require fine imaging of seabed strata and structures.The highresolution marine seismic exploration based on a high broadband sparker source is an important approach to reveal seabed stratum and reservoir structure,and identify geohazard.To optimize the performance of sparker seismic source,we investigated the electro-acoustic characteristics of spark discharge under conditions of different charging voltages and electrode numbers.Results show that the sound source level increased with the increase of the charging voltage,whereas the main frequency decreased when the charging voltage increases.In addition,it was found that the charging capacitance had more obvious influence on the main frequency than the sound source level did.Although the load energy decreased with increasing electrode number,the sound source level still increased but the main frequency decreased.Meanwhile,the primary to bubble(P/B)ratio increased with the increase of the electrode number.To gain a deeper insight into the electro-acoustic characteristics,we investigate the relationship between sound source level and power peak,from which a good correlation was observed.A more practical statistical analysis on the rise rate of current was processed,and a perfect logarithmic function was derived.Furthermore,we found that the main frequency was most possibly subjected to the electrical energy,especially the charging energy per electrode.The results indicate that the charging energy per electrode less than 10 J could increase the main frequency to above 300 Hz.At last,the main frequency could be reduced to 20 Hz when the charging energy of a single-electrode discharge was enhanced to over 4 kJ.This study shall be helpful in developing a sparker seismic source and improving the performance for marine engineering exploration and geohazard assessment.

基于PIES观测东沙群岛附近声传播变化

本研究旨在将PIES观测数据应用于海洋水声环境的监测。利用一次南海PIES观测数据,反演得到温盐剖面,进而计算声场信息。结合观测期间的暖涡及台风事件对反演及计算结果进行了分析验证。结果表明,PIES能够在长期连续观测中较为敏感地捕获上层水体及表面声道的变化特征,为水声通信、探测及潜航路径规划等提供参考,在水声研究及海洋军事环境保障中都具有良好的应用前景。

船用立式离心泵流噪声特性分析

为了降低舰船在航行时的噪声,对船用立式离心泵内部流动噪声的特性进行研究。基于计算流体动力学(CFD)数值仿真方法计算某型立式离心泵的非定常流场,分析其在不同位置处的脉动压力特性,并通过试验验证流场计算结果的准确性。提取在3种工况下通过非定常流场计算得到的叶片旋转偶极子和蜗壳固定偶极子声源信息,在LMS Virtual lab中进行内部流动噪声计算,并分析其流动噪声特性。研究结果表明:叶轮出口不均匀的射流-尾迹结构和叶轮与隔舌的动静干涉作用是立式离心泵叶轮部位和蜗壳部位产生脉动压力的主要诱因;内场噪声与脉动压力直接相关,噪声频率特性与脉动压力频率特性一致,主要峰值频率集中在叶频和倍频处;固定偶极子声源和旋转偶极子声源均对立式离心泵内场流动噪声有很大贡献,与旋转偶极子声源相比,固定偶极子声源对进出口噪声的影响更大。研究成果可供船用立式离心泵减振降噪和低噪声设计参考。

Fine Sand and Clay Sediment Acoustic Properties of the Novel Sediment Sample from the Arabian Sea:Experimental Investigations and Biot−Stoll Model Validation

The present study explores the physical and acoustic characteristics of fine sand and clay in novel seabed marine sediments from of Pakistan coastline of the Arabian Sea.The measured physical parameters included mean grain size,mass density,bulk density,salinity,porosity,permeability,pore size and mineralogical composition.Acoustic properties,including sound speed and attenuation,in the high frequency range of 90-170 kHz were analyzed.A controlled laboratory setup with the acoustic transmission method and Fourier transform techniques was utilized to examine the sound propagation and absorption of novel seabed sediments.The standard deviation of mean sound speed in fresh water was 0.75 m/s,and attenuation was observed in the range of 0.43 to 0.61 dB/m.The mean sound velocity in sand and clay varied from 1706 to 1709 m/s and 1602 to 1608 m/s,respectively.Corresponding average attenuation was observed at 80 to 93 dB/m in sandy sediments and from 31.8 to 38.6 dB/m in clayey sediments.Sound velocity variation within sandy sediment is low,consistent with expected results,and smaller than the predicted uncertainty.However,clay sediment exhibited a positive linear correlation and low sound speed variation.Attenuation increased linearly with frequency for both sediments.Finally,the laboratory results were validated by using the Biot−Stoll model.The dispersion of sound speed in sandy and clayey sediments was consistent with the predictions of the Biot−Stoll model.Measured attenuation aligned more with Biot−Stoll model predictions due to improved permeability,tortuosity and pore size parameter fitting.

多波束测深系统在人工鱼礁投放量估算中的应用

人工鱼礁投放量是海洋牧场建设的重要环节,为了实现鱼礁投放量的估算,利用多波束测深系统对投礁海域进行全覆盖扫测,获取投礁区域水深数据,构建水下三维模型,并利用空间分析软件识别出71块投礁重点区域,累计投礁面积约56710.916 m2,投放量约57772.205 m3,初步确定了人工鱼礁的投放位置、面积和体积等信息,实现了人工鱼礁投放的科学估算,为后续海洋牧场的建设和监测提供了一种有效的技术手段。

失事目标水中搜寻技术发展现状及趋势

针对近年来海洋事故日益增多的问题,本文研究分析了水中搜寻技术发展现状及趋势。本文以水中搜寻技术为对象,对当前水中失事目标进行了分类,分析了水中搜救策略研究现状,讨论了3种数据与模型搜寻方法。阐述了水中搜寻平台与设备发展情况,结合当前搜寻技术的不足,从增强失事目标定位能力,提高水下机器人水下搜寻能力与智能化,提高集群化、多平台协同组网能力和提高声学探测设备性能与数据处理能力4个方面给出了水中搜寻技术发展趋势。

海底沉积物岩芯横向声学测量系统的标定

水平轴向测量技术相对成熟,但较难获取海底沉积物的无扰动分层声学特性,采用横向测量技术可以解决这一问题。文章研究了海底沉积物岩芯横向测量技术,将水作为海底沉积物测量的参考标准,进行测量系统的标定。提出了等效换能器的概念,将样品以外的声传播介质整合成等效换能器的一部分,标定测量等效换能器声延时和声传播初始能量。以水为标准介质,分别采用33、80、100 kHz三种频率的声学换能器,以及75、90、110 mm三种管径的聚氯乙烯(Polyvinyl Chloride,PVC),测量所得的水中的声速与标准计算水中的声速具有一致性,其中以采用80 kHz频率声学换能器和90 mm管径PVC管测量时的声速误差最小,选用此状态进行标定,得出当隔水耦合测量法换能器相对距离为142.02 mm时,标定的等效换能器声延时为45.88±0.08μs,等效换能器声传播初始能量(以接收换能器的接收电压表示)为0.86±0.03 V。应用标定的等效换能器声延时和声传播初始能量测量海底沉积物。计算得到声速和声衰减系数符合黏土质粉砂的声学特性。

Statistical correlation of physical parameters with sound velocity in marine sediments of South and East China Seas

The statistical correlation of the physical parameters with sound velocity in marine sediments is presented based on the data acquired from both South and East China Seas. Firstly the optimal empirical equation is obtained by app lying the least-squares method. Then the important parameters which mainly affect the sound velocity in sediments are identified. Finally the patterns of marine sound velocity structures are presented and discussed.

有效声速泰勒级数逼近的适用条件

在水下高精度声学定位和声纳水深测量中,需要高精度的有效声速参量。在实际中,精确计算有效声速需要声线跟踪算法,但计算成本较高。有效声速的泰勒级数逼近作为一种有效声速的近似逼近方法,可避免大量计算成本。讨论了有效声速泰勒级数逼近公式的不同阶数逼近情况,特别是给出了两类有效声速泰勒级数逼近公式的适用条件,以及他们随高度增大适用性和逼近精度的变化。研究表明,当声速剖面稀疏时,宜采用谐波平均声速下的泰勒级数改正公式;当高度角小于50°时,有效声速泰勒级数逼近精度出现明显的衰减。

考虑声线弯曲和深度约束的海洋大地基准网定位仿真分析

为了优化海洋大地基准网性能,本文研究了附加深度约束的海洋大地基准网定位方法及其观测模型设计矩阵解法,在此基础上考虑声传播路径弯曲,仿真分析了综合声学浮标、潜标和海底基站的海洋大地基准网定位性能。结果表明,潜标深度和基站间距均影响基准网的有效测站个数分布,且基站间距影响基准网的信号覆盖范围,适当扩大基站间距和增加潜标深度可有效提高基准网定位精度。相关结果可为海洋大地基准网的建设及应用提供参考。

Underwater Noise Target Recognition Based on Sparse Adversarial Co-Training Model with Vertical Line Array

The automatic identification of underwater noncooperative targets without label records remains an arduous task considering the marine noise interference and the shortage of labeled samples.In particular,the data-driven mechanism of deep learning cannot identify false samples,aggravating the difficulty in noncooperative underwater target recognition.A semi-supervised ensemble framework based on vertical line array fusion and the sparse adversarial co-training algorithm is proposed to identify noncooperative targets effectively.The sound field cross-correlation compression(SCC)feature is developed to reduce noise and computational redundancy.Starting from an incomplete dataset,a joint adversarial autoencoder is constructed to extract the sparse features with source depth sensitivity,aiming to discover the unknown underwater targets.The adversarial prediction label is converted to initialize the joint co-forest,whose evaluation function is optimized by introducing adaptive confidence.The experiments prove the strong denoising performance,low mean square error,and high separability of SCC features.Compared with several state-of-the-art approaches,the numerical results illustrate the superiorities of the proposed method due to feature compression,secondary recognition,and decision fusion.

多波束测深系统在海洋航道测量中的应用研究

随着科学技术的进步,我国海洋航道测量中出现了多种测量手段,其中,多波束测深系统是目前国家海洋探测广泛应用的手段之一,有良好的测深效果。其通过扫测已知碍航物,可以呈现更生动的海底地貌三维影像,数据成果的分辨率及准确度更高。文章概述了多波束测深系统在海洋航道测量中的应用,介绍了多波束系统的测深工作原理、操作流程、数据的误差来源,分析了该测深系统的优势及特点,以供参考。

声呐技术在海洋资源勘探中的应用与发展

文章介绍了声呐技术的基本原理,重点讨论声呐技术在海洋矿产勘探、海洋生物资源勘探和海洋地质勘探中的应用。同时,探讨声呐技术在海洋资源勘探中面临的挑战和发展趋势,分析声呐技术在海洋资源勘探中的未来发展。通过不断创新和改进,声呐技术将为海洋资源勘探提供更准确、高效的探测手段,为海洋资源的开发和利用做出更大的贡献。

海洋测绘中的测深技术探讨

海洋测绘是对海洋环境进行科学研究和资源勘探的重要手段之一。在海洋测绘的过程中,测深技术是获取海底地形信息的重要途径之一。多波束测深技术、机载激光测深技术和侧扫声呐技术是海洋测深领域中主要技术手段。未来,这些技术都将继续发展,并朝着提高测量精度、加快网络信息服务建设、优化测深技术、智能化、综合应用和大数据应用等方向不断演进。这些技术的发展将促进海洋资源勘探和海洋环境保护等方面进一步发展。

船舶居住舱室隔声、减振典型技术研究

随着船舶居住舱室舒适度越来越受到重视,隔声、减振、降噪技术在船舶内舾装中也越来越受到重视。本文通过梳理相关法律法规关于船舶居住舱室的规定,从设计方案、材料选型、工艺节点等几个方面进行分析,形成典型的隔声、减振技术方案,满足不同舒适度等级居住舱室建造要求,为船舶居住舱的设计建造提供参考。

海上起重机过载保护系统分析

基于实际海上起重机的设计工作,根据国际知名船级社以及行业组织的规范要求,对甲板起重机的过载保护系统进行分析研究,阐述了过载保护系统设计的重要参数和设计考量,以期为起重机设计工作者提供借鉴。

多频海底声学原位测试系统研制和试用

海底沉积物的声学特性（最重要的是声速和声衰减）以及它们与物理（包括土力学）特性之间的关系是沉积物声学中两个重要的研究项目．介绍了新研制的实时监控多频海底声学原位测试系统．该系统可测量浅表层沉积物的声速．探测频率为8，10，12，15kHz，可根据实际情况选择发射波形、接收增益和采样长度，采样率为0．5～2．0MHz，工作水深为300m．系统具有倾斜传感器、8通道扩充等功能．用该系统在杭州湾测得了四种频率的沉积物原位声速．

水下爆破的声压测量及其对海洋生物的影响

简述水下爆破的物理现象．根据水下爆破所产生的声波的特点，介绍一种可行的声压测量方法．同时，通过对爆破点附近的一些养殖海洋生物的检测，讨论水下爆破对海洋生物的影响，为兼顾海洋开发与海洋渔业生产提供参考．

海洋地球物理探测技术及其在近海工程中的应用

介绍了多波束测深、侧扫声纳测深、浅地层剖面测量、高分辨率地震测量和海洋磁力测量等五项海洋地球物理探测技术的最新进展和简单工作原理,给出了目前国内外广泛使用的主要技术产品型号以及主要参数和性能和展示了这些技术近年来在近海工程,例如海缆(海底光缆、电缆和管线等)路由调查、跨海大桥和海底隧道工程地质环境评价、工程灾害因素分析、海底目标物寻找和水下考古等方面的应用实例。

海洋测深数据的抗差Kalman滤波

从线式测深模式要求出发,构建了海洋水深测量过程中的测船位置滤波模型和深度数据的滤波模型,并在此基础上,给出了测线上位置数据和深度数据Kalman滤波的一般解和抗差解,并结合海洋水深测量特点,构建了满足水深数据剔除异常值的截断权函数和滤波方案,实例分析表明,抗差滤波方法能够有效地控制测船位置粗差,在选择截断权函数情况下,抗差滤波方法能够有效地剔除水深跳点和假水深。