小型水下自航行平台控制体系开发

以小型、经济、易扩展为目标,采用模块化设计思想,开发了一种基于CAN总线的递阶一分布式水下自航行平台控制系统,并重点考虑了安全可靠性,对各节点负载进行了优化分配。实际应用表明,该控制系统结构简单、性能可靠、传输率高,能够满足平台工作环境复杂多变的要求。     

水面运动目标跟踪监控系统的设计与实现

本文围绕海上无人值守平台周界安防技术需求,以800 m范围内的快艇、渔船、客轮和商船为航行目标构建运动目标跟踪监控系统,并集成开发了基于水下被动声学检测和水上云台控制的光学视频系统为一体的声光一体化监控系统,设计了一套基于深度学习的目标检测算法,实现了对水面航行目标的跟踪检测与分类识别。本文在目前基于单一方法进行水面目标跟踪的基础上进行了突破,系统综合了水听器远距离目标监控跟踪和近距离的水面视频监控目标识别,当两者同时确认目标,由声警器发出警报驱离可疑目标,系统将水下声学监控和水面视频监控有效结合,极大地降低了平台的误报概率,同时实验测试结果表明该系统可有效实现对4类水面航行目标的跟踪检测和特征提取,且改进后的算法可有效提升目标检测效果与识别精度,具有较好的鲁棒性和有效性。     

水下光通信技术的研究与展望

水下光通信(Underwater Optical Wireless Communication,UOWC)是一种新型的水下通信技术, 具有保密性好、可靠性高等优点,对于构建全光立体通信网络以及 6G 空天海地一体化全方位通信有重要的意义。分析了水下光通信相较于其他传统水下通信方式的优点,对水下光通信发展历程与进展进行了综述,对比了水下光通信 2 种主流光源：激光光源和 LED 光源。针对现阶段水下光通信面临的难题,提出了一种完善的水下光通信系统框图,并研制出相应的硬件系统,完成了水下通信调试。水下光通信是一种切实可行的新型通信方式,兼具灵活、保密、高速率等特点,在未来的 6G 时代中将会得到进一步的发展和应用。     

基于双冗余以太网通信的气象实时观测数据采集网络传输系统的设计与实现

随着以太网技术应用的日趋成熟,在海洋和大气观测领域,人们希望对传统不具备网络通讯能力的观测仪器进行智能化和网络节点化改造。设计和实现了一套气象实时观测数据采集与网络传输系统。该系统采用基于ARM的嵌入式系统集成设计方案,实现了对外部传感器实时观测数据的采集和以太网通信。作为多级网络系统中的一个网络节点,该采集传输系统采用双冗余以太网通信接口设计,使系统中的双路以太网在一路局部故障或线路受损时可以自动冗余切换。这一设计特点大幅提高了作为网络节点的数据采集传输系统在与外部其他设备通信时数据传输的可靠性。通过在以太网条件下,网络闭环控制运行试验等测试,证明所开发的气象实时观测数据采集网络传输系统运行稳定可靠,双冗余以太网接口切换正常,数据采集传输及时准确,可完全满足实际应用的需要。     

自治水下机器人机械手系统协调运动研究

简单描述了自治水下机器人搭载的三功能水下电动机械手的设计,鉴于自治水下机器人-机械手系统运动学冗余、内部可能干涉以及载体圆筒式外形等特点,将惩罚调节因子引入系统运动学伪逆矩阵,保证了关节在允许范围内运动,避免载体大幅度姿态变化及载体与机械手之间的干涉,同时采用梯度投影法优化海流作用下的系统推力。仿真表明,该算法在解决系统冗余度的同时,有效地协调多任务下的系统动作。     

基于水下三维传感器网络的海洋环境立体监测系统关键技术研究

深入分析了我国海洋环境监测技术的不足与现实需求,提出一种基于水下三维传感器网络的海洋环境立体监测系统,探讨了系统的组成、架构及其涉及的关键技术。设计了可自主沉浮的水下传感器节点,探讨了水下传感器节点间、系统与控制中心间的通信方式,对网络拓扑结构进行了三维仿真,最后对水下三维传感器网络的应用前景进行了展望。     

面向智慧海洋的MIMO探测通信一体化波束成形设计

随着智慧海洋的不断发展,海洋研究中海洋信息的可靠获取、高速传输和高效处理越来越重要。为此,考虑一个面向智慧海洋的多输入多输出（Multiple-Input Multiple-Output,MIMO）探测通信一体化系统,在同一平台上共享相同的频谱资源来同时实现水下目标探测与通信。首先,对基于通信信号以及基于通信和探测信号叠加的2种一体化波形构成方法进行研究,在满足总功率及通信用户信干噪比需求的约束下,最小化MIMO探测发射波束图匹配误差和互相关图。然后,针对建立的2种波束成形设计问题,将其转化为二次半定规划问题并采用半正定松弛算法进行求解,得到探测通信一体化波束成形矩阵。最后,仿真结果验证了MIMO探测通信一体化波束成形设计的可行性。     

水声通信及组网的现状和展望

水声通信是海洋中无线信息传输的主要技术手段。水声通信技术在海洋环境监测、水下航行器/载人潜水器作业等方面有着广泛应用。同时,水声信道传输状态多变、海洋作业环境恶劣,对通信算法和设备可靠性有较高要求,水声通信及组网成为目前的研究热点。文中面向海洋环境监测领域,从水声通信物理层技术、网络技术及组网应用等方面进行介绍,并对未来技术趋势进行展望。     

水声通信半物理仿真平台设计与应用

信道自身的复杂性和现场级试验的高投入、高风险限制了水声通信技术的发展。针对高效率水声通信技术研究的需求,提出1种水声通信半物理仿真平台水声通信半物理仿真平台(A Hardware-in-Loop Simulation Platform for Underwater Acoustic Communication)。水声通信半物理仿真平台以可配置水声Modem为核心,包括现场测试采集系统、算法仿真评估系统、算法实现装载系统、水声波形存储播放系统。基于建立的水声通信半物理仿真平台,进行水声直接序列扩频通信系统的半物理仿真研究,结果表明水声通信半物理仿真平台可有效提高水声通信技术的研究效率。     

基于相关性分析的水下定位异常数据校正及丢失数据修补方法

超短基线是实现水下拖体设备精确导航定位的必备设备,是目前我国在国际海底区域进行资源深入调查研究的重要装备。受水声信号传播损失、多径效应和其它设备噪声等因素的影响,超短基线水下定位数据存在诸多异常点,已严重影响水下定位数据的可信度和使用。针对该问题,本文提出并实现了一种基于相关性分析的剔除随机异常点和回归填充改正算法,并采用国际海底区域实测水下定位数据对算法可靠性进行了验证,同时采用模拟仿真方法对小时间尺度的定位数据进行了预测对比,取得较好效果。结果表明,该算法快捷、有效,有望在后续国际海底区域调查中推广应用,为国际海底资源调查水下装备的准确定位提供直接服务。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.