基于K-means聚类与数学形态学的侧扫声呐图像目标轮廓自动提取方法

针对侧扫声呐图像斑点噪声强、背景海底散射干扰严重,海底目标轮廓自动提取困难的问题,提出了一种基于K-means聚类与数学形态学相结合的海底目标轮廓自动提取算法。为克服噪声干扰,该算法首先利用中值滤波去除侧扫声呐图像中的强斑点噪声;然后采用K-means聚类算法对侧扫声呐灰度图像进行分割,并二值化,除去大部分海底背景噪声,初步提取出目标;接着利用数学形态学运算去除提取结果中的孤立噪点,并填充目标内部孔洞,得到连续化、圆滑的目标边缘;最后对处理后的侧扫声呐图像进行边缘检测,提取出目标轮廓。实验结果表明:该算法思想简单易行,具有很强的克服背景噪声的能力,自动提取的目标轮廓连续性较好,结果准确可靠。目前,在侧扫声呐图像目标轮廓提取过程中,主要采用人工方式,自动性较差,效率较低。本文算法可以实现目标轮廓的自动提取,提高效率,具有较强的实用价值。     

海底管道风险分析中自然影响因素评分标准初探

借鉴美国学者Muhlbauer提出的管道风险评分法,对渤海海底输油管道系统进行自然风险辨识,并根据渤海海域环境特征对自然环境影响指标评分标准进行了初步研究,形成适合渤海海底管道风险评价的评分标准体系,为渤海海底管道风险分析提供技术依据.     

论旁侧声纳图像镶嵌技术

本文介绍了新一代旁侧声纳系统的技术性能;论述了关于海底声纳图像的镶嵌方法;讨论了影响声纳镶嵌图质量的若干问题;还通过区域性海底地貌研究,局部场地调查,搜寻海底目标等实际例证来阐明声纳镶嵌图的广泛用途。     

基于FieldⅡ的多波束海底检测性能仿真

基于Field Ⅱ声场仿真工具建立了仿真模型,模拟了平坦以及海底有凸起目标时的海底地形,分别采用常规波束形成器和超波束形成器对模拟的海底回波数据进行处理,结果表明超波束形成器分辨目标的性能更优;应用Monte Carlo方法进行仿真实验,结果表明基于超波束形成器的WMT算法深度估计均值更接近真值、标准差更低,可以有效提升多波束海底检测性能。     

深海底矿区登记制度与我国的申请（二）

5.第一批申请者的登记情况在1987年举行的海底筹委会第五届夏季会议上,以及嗣后召开的总务委员会会议上,先后审查批准了印度、法国、日本、苏联登记为先驱投资者的申请。总务委员会对这些先驱投资者的申请书在审查批准时,首先确认它们对海底筹委会所作的下列保证:一是申请区是国际海底区域的一部分,不在任何国家的管辖范围之内;二是其所申请的海底矿区没有重叠问题,也没有重复申请国际海底多金属结构的矿区问题;三是一旦申请得到批准,并接到筹委会的通知,将向海底筹委     

海底小目标声呐图像一维最大熵分割的改进方法

作为海洋高新技术,水声技术日益成为海洋水下探测的主要手段,而且有时是惟一的手段(比如对浑水或对远距离的情况).海底物体搜索、海底救捞、海底探宝、海底“黑烟囱”探测、海底施工以及海洋军事活动(如探测水雷)等多方面都涉及海底小目标(这里的“目标”泛指物体,包括各种人工制造物和自然形成物)探测.对海底小目标探测是一个困难而有意义的课题.高分辨成像声呐在海底小目标探测方面具有良好的应用前景.将高分辨成像声呐应用于海底小目标探测,图像处理是关键.图像分割是图像处理中的主要问题,也是机器视觉领域低层视觉中的主要问题,同时它又是一个经典难题.     

多波束和侧扫声纳系统在海底目标探测中的应用

介绍了多波束测深系统和侧扫声纳系统的工作原理,通过实例说明了多波束测深系统和侧扫声纳系统在海底目标探测的工作流程,总结出两种探测系统在探测海底目标上的优缺点,说明了多种探测手段的综合应用是海底目标探测技术的发展方向。     

基于LBL的海底管节施工局域控制网建立

针对现有水下定位方法在精度和效率上的不足,提出了一种基于LBL建立海底局部控制网的方法。首先根据对称原则,给出了海底控制网布设方法;其次,给出了圆走航海底绝对基准传递方法和数据处理方法;最后,建立了海底控制网无约束和约束平差模型,实现了控制点绝对坐标的高精度确定。将控制网布设、测量和数据处理方法应用于实际工程,300m水深情况下,取得了优于5cm的定位精度。     

小尺度海底沉积物的声衰减特性研究

为研究小尺度海底沉积物样品的声衰减特性,作者提出了用声学探针测量海底沉积物声波幅值的新方法,对沉积物样品扰动小,两个测量点的距离可小于波长,为海底沉积物微观声衰减测量提供了新手段。作者用小于波长的间隔逐点测量了沉积物的压缩波幅值,数据分析表明沿沉积物柱状样全长的声衰减满足指数衰减模型。目前主要用同轴差距衰减测量法获得海底沉积物声衰减数据,但该方法不能辨识声衰减模型,因此不同海区的测量结果难以建立联系。对此作者又提出用声吸收系数反演的幅值比与声衰减系数反演的R值(两种幅值比的比值)作评价依据,分析了垂直轴差距衰减测量法获得的南海海底沉积物声衰减测量数据,发现部分沉积物样品声衰减的R值远大于1,其声衰减不满足指数衰减模型。在声衰减满足指数衰减模型的条件下,用Hamilton的声衰减和频率经验公式预报的南海沉积物声衰减比与作者用声学探针测量海底沉积物所得的声衰减比对比,通过对R值分析得出Hamilton的声衰减和频率经验公式可以预报南海沉积物声衰减比的范围。作者提出的声学探针测量海底沉积物声衰减的方法的优点是既能获得声衰减数据又能辨识声衰减模型,不同海区测量的沉积物声衰减比可用R值建立联系。     

多波束海底声像图的形成及应用研究

在探讨多波束海底声像图形成原理基础上,重点研究多个扇面、多个条带的反向散射强度数据拼接、镶嵌方法,将海底反向散射强度值向图像灰度值转换,最后形成海底声像图,为海底地貌解译、海底目标物探测以及海底底质类型划分提供判读依据。     

探猎雷装备探测概率分类方法研究

探猎雷装备作为海军反水雷部队的主要装备，其探测应用研究对提高建制式反水雷装备的作战效能具有重要意义。从作战部队探猎雷实战使用流程出发，结合探猎雷装备应用现状，提出了声呐探测目标的概率分类方法，建立了探测概率分类方法模型，对实际应用需解决的问题进行了探析。对开展海区水雷目标数量评估、目标的识别比对以及声呐探测航次优化等装备作战运用有一定的启发和促进作用。     

Robust leader-follower formation tracking control of multiple underactuated surface vessels

This paper is concerned with the formation control problem of multiple underactuated surface vessels moving in a leader-follower formation.The formation is achieved by the follower to track a virtual target defined relative to the leader.A robust adaptive target tracking law is proposed by using neural network and backstepping techniques.The advantage of the proposed control scheme is that the uncertain nonlinear dynamics caused by Coriolis/centripetal forces,nonlinear damping,unmodeled hydrodynamics and disturbances from the environment can be compensated by on line learning.Based on Lyapunov analysis,the proposed controller guarantees the tracking errors converge to a small neighborhood of the origin.Simulation results demonstrate the effectiveness of the control strategy.     

Mine avoidance techniques for underwater vehicles

It is shown that by implementing certain mine avoidance techniques, an underwater vehicle equipped with an obstacle avoidance sonar (OAS) and a navigation system can safely navigate an unknown minefield. The mine avoidance techniques take into account the physical limitations of the sonar and the navigation system, the maneuverability constraints on the underwater vehicle, and the required safe standoff distance from all mines. Extensive computer simulations have verified the mine avoidance capability in more than 50 different minefields. In all 50 simulations the vehicle reached a predetermined end point and maintained at least the specified, minimum safe standoff distance from each mine. The simulation accurately models the major difficulties associated with the sonar, the navigation system, and the vehicle dynamics. The sonar model includes surface, bottom, and volume reverberation; thermal, ambient, and flow noises; actual receiver and projector beam patterns; and false alarms and missed detections. The navigation system model contains the effects of biases, random noises, and scale factor errors. The vehicle dynamic model simulates angular velocities and accelerations associated with underwater vehicles     

水雷目标识别中的数据融合技术

主动声纳发射声信号“照射”被识别目标,并从目标产生的回波中提取出目标的特征信息,结合可能得到的先验知识,对目标的类别作出判断。论文偿试把现代信号处理技术与信息融合技术相结合,应用到具体的水雷目标识别领域,以提高水雷回波识别系统的准确性和可靠性。     

VPN安全性与地址冲突研究

为了解决校园网络升级改造过程中引入DMZ与VPN技术后,导致的内网资源安全性降低与虚拟IP地址碰撞的难题,在传统VPN解决方案基础上,提出虚拟IP地址生成算法与IP地址连接池的思想。异地用户通过VPN访问内网资源时,必需使用IP地址连接池来获取虚拟IP地址,实现虚拟IP地址分配的动态管束,有效控制虚拟IP地址的随意分配,避免因争夺虚拟IP地址资源而产生的碰撞问题。这种方法对于提高VPN网络的安全性和访问效率,遏制黑客通过匹配IP地址的方式入侵内网、保护内网资源安全与解决地址冲突问题非常有效。     

Punctuated recovery of sediments and benthic infauna: a 19-year study of tailings deposition in a British Columbia fjord.

Sediment organic and metal chemistry, benthic infauna and tissue contaminants surveys have been conducted over 19 years before and following tailings deposition from a metal (Mo, Pb, Zn) mine in Alice Arm, a British Columbia fjord. We found changes in benthic fauna and habitat after tailings disposal to be predictable in terms of sediment chemistry and faunal recolonization. What was not predictable was the timing and extent of slope failure or resuspension following abandonment. These events can have essentially the same or greater effect than the initial tailings disposal and produce long-term unpredictability particular to cases of submarine disposal on slopes. The present study focused on the submarine deposition of 4 x 10(6) tonnes of tailings during an 18-months period ending October 1982. When the mine closed, gross defaunation had occurred at three stations in the tailings path, and two others showed recent defaunation and recolonization. A year later, a large tailings slump near the outfall transported tailings to the deep basin; fauna were impoverished both in the slump region and through most of the deep basin. Declining metal concentrations in surface sediments was accompanied by considerable recovery of fauna 3 years after the mine closed. Nevertheless, fauna at the three stations defaunated at the time of mine closure could still be statistically distinguished from all other stations due to high abundances of small opportunistic polychaetes and bivalves. A resuspension in tailings between 1988 and 1990 coincided with a moderate decline in abundance of all macrofauna taxa. From 1989 to 1995 recovery toward natural sediment conditions was evident as increasing organic content together with the highest faunal biomass values found during the study. Small polychaetes were the first recolonizers in defaunated areas, whereas small bivalves were more tolerant of moderate tailings deposition. By 1989 and 1995 small colonizers had declined and amphipods and larger echinoderms had increased. Dominant species patterns and exceptionally high biomass values in 1995 show that the largest fauna did not recover until much later than smaller taxa. One genus of bivalve (Yoldia spp.) accumulated metals in a pattern similar to the sediment chemistry, indicating that the metals from the most recent mine had entered the benthic food chain. It is not possible to tell from this study whether biota were affected by toxicity from metals. However, many of the observed biotic effects could be caused by physical disruption from tailings.     

基于虚拟仪器的水下目标二维角估计

利用LabVIEW软件，通过8通道数据采集卡和均匀圆阵对水下目标的噪声进行采集和处理。结合一维直线阵波束形成理论，实现了对水下目标二维方向角估计实验研究和算法验证。实验证明利用虚拟仪器方便地实现了对水声信号的采集、处理，以及在方位估计时，为传感器布阵和算法的确定提供参考。     

基于时间-Doppler分析的海杂波背景下小目标检测

为解决传统舰载雷达和岸基雷达很难检测出海杂波背景下小目标的现状,提出一种基于时间-Doppler分析法来检测小目标。该算法用离散短时傅里叶变换对实测海杂波数据分析得到不同距离门的时间-Doppler速度图,通过分析和比较距离门含有小目标的Doppler展宽和Doppler速度大小与其他距离门不含有小目标的Doppler展宽和速度大小的不同,即可检测出小目标。实验证明,该算法是有效的。     

On a new wave energy absorber

It is a commonly held opinion that only a forced resonance is possible between random wind-generated waves and wave energy absorbers; the forced resonance being pursued by means of devices for phase control. We show, instead, that it is possible to obtain an impressive natural resonance between random wind-generated waves and a new kind of absorber beneath the sea level. The proof is given through a small scale field experiment. This finding should enable us to defend coasts with a very low environmental impact and to use breakwaters for converting large quantities of wave energy into electric power.     

地层测试评价仪在渤海油田的应用

电缆地层测试是求取储层流体性质、进行储层评价最为直接的方法之一。地层测试评价仪（FET）是国产新一代地层测试评价仪器，不仅可以精确测量地层压力并根据压力剖面确定地层流体类型和油气水界面，而且在目的层取样时可以抽排污染流体、实时检测地层流体特性，对确定地层流体性质和分析流体成分起到了重要作用，同时它也可以计算地层渗透率，进行储层产能预测。通过在渤海油田的成功应用，简单介绍FET的基本工作原理和主要用途，重点论述其优越性和局限性，以及在渤海油田成功应用的典型实例，这对FET在其它油田的推广应用具有参考意义。