一种多波束声呐在船舶水下安检系统中的应用

针对船舶水下安检技术发展现状,介绍了一种应用于船舶水下安检的多波束声呐系统的组成和原理,开展了一系列的湖上试验。通过对试验船只水下部分的声学扫描,得到了船底三维图像及船只吃水信息。试验结果表明,系统可应用于船底异物检查、船只吃水检测等船舶水下安检领域。     

一种使用二进制图像特征的被动声呐自动分类方法（英文）

This paper proposes a new method for ship recognition and classification using sound produced and radiated underwater. To do so, a three-step procedure is proposed. First, the preprocessing operations are utilized to reduce noise effects and provide signal for feature extraction. Second, a binary image, made from frequency spectrum of signal segmentation, is formed to extract effective features. Third, a neural classifier is designed to classify the signals. Two approaches, the proposed method and the fractal-based method are compared and tested on real data. The comparative results indicated better recognition ability and more robust performance of the proposed method than the fractal-based method. Therefore, the proposed method could improve the recognition accuracy of underwater acoustic targets.     

水下地形辅助导航中局部地形特征的快速提取方法（英文）

Terrain matching accuracy and real-time performance are affected by local underwater terrain features and structure of matching surface. To solve the extraction problem of local terrain features for underwater terrain-aided navigation(UTAN), real-time data model and selection method of beams are proposed. Then, an improved structure of terrain storage is constructed, and a fast interpolation strategy based on index is proposed, which can greatly improve the terrain interpolation–reconstruction speed.Finally, for the influences of tide, an elimination method of reference depth deviation is proposed, which can reduce the reference depth errors caused by tidal changes. As the simulation test shows, the proposed method can meet the requirements of real-time performance and effectiveness. Furthermore, the extraction time is considerably reduced, which makes the method suitable for the extraction of local terrain features for UTAN.     

一种新的宽带声呐波束域背景均衡方法

提出一种新的宽带波束域背景均衡方法--差分邻域均衡算法,通过两步实现波束域的背景均衡.与波束域OTA背景均衡算法相比,差分邻域均衡法更易于工程实现.计算机仿真结果表明,差分邻域均衡算法在均衡背景噪声的同时可以较好的保留目标信号,改善了声呐的显示效果,使目标方位更加清晰.     

多波束测深相位检测法中一种有效的相位差序列提取方法

比较了多波束测深系统相位检测法中可能使用的几种相位差序列提取方法，采用数据压缩和动态平均的方法，得到能保留原数据固有规律的新相位差序列，它对于相位检测法的实时实现有重要作用。     

一种基于节点鉴别的水下传感器网络协同干扰方案（英文）

Cooperative jamming (CJ) is one of the important methods to solve security problems of underwater acoustic sensor networks (UASNs). In this paper, we propose a Cooperative Jamming Scheme based on Node Authentication for UASNs to improve the effect of CJ by selecting suitable jamming source for found illegal nodes. In the node authentication, all nodes will be identified by their trust value (TV). TV is calculated according to three types of evidence:channel-based trust evidence, behavior-based t...     

多波束测深系统的精度评估方法研究

随着科学技术的不断进步,人们对世界的探索不断加深。多波束测深系统有着数据精准,检测方法适应海洋环境较强的特点。但是多波束测深系统的精度评估有几种方式,文章便就相应的状况进行分析研究,提出相应的观点。     

一种高精度声呐波束发射系统的设计与实现

为解决传统声呐发射系统利用移位寄存器的冗余效应的设计方法所引起的精度不高问题,介绍一种采用DSP芯片与FPGA芯片结合设计的声呐发射系统的方法.该系统可同时产生多路信号,每路信号均可独立调节、设定,且各路信号可严格同步,并可按要求设定时延控制、循环发射等功能,各路信号间的延时精度可达200 ns,从而为波束发射系统的开发提供了一种新的思路.实践表明,该方法具有实现过程简单、精度较高的特点,适合于工程应用.     

SVR辅助SINS-DVL的水下机器人组合导航方法

多普勒计程仪(DVL)在水下导航系统应用越来越广泛。当海底环境发生变化时,DVL会发生数据刷新频率不稳定,数据无效等情况。为了提高导航的可靠性,本文提出了一种变训练集的SVR回归方法,对DVL的数据进行预测。根据水下机器人的速度变化率和加速度变化率调节训练集大小。把捷联惯导(SINS)的东向和北向速度作为输入,DVL东向和北向速度作为输出对模型进行训练。根据SINS的数据输出频率,选取合适的预测数据输出频率进行仿真。仿真发现算法有效地提高了SINS/DVL组合导航的精度,并在DVL数据无效时,有效地抑制误差,提高导航系统的稳定性。     

一种基于双曲波束形成的多波束底检测技术

基于能量的底检测技术在多波束测深系统中被广泛采用,但常规波束形成的波束宽度受到阵列孔径的限制,且旁瓣较高,造成能量泄漏,对基于幅度的海底检测技术造成一定难度,影响系统的检测性能.本文在分析双曲波束形成波束特性的基础上,将这种技术应用到基于能量的多波束底检测技术中,并通过实验数据分析,验证了在基于能量的底检测中引入双曲波束形成技术,可以在减小波束宽度的同时抑制旁瓣,从而有效提升系统检测性能.     

一种水翼空化的被动控制方法（英文）

This paper introduces a new idea of controlling cavitation around a hydrofoil through a passive cavitation controller called artificial cavitation bubble generator(ACG). Cyclic processes, namely, growth and implosion of bubbles around an immersed body, are the main reasons for the destruction and erosion of the said body. This paper aims to create a condition in which the cavitation bubbles reach a steady-state situation and prevent the occurrence of the cyclic processes. For this purpose, the ACG is placed on the surface of an immersed body, in particular, the suction surface of a 2 D hydrofoil. A simulation was performed with an implicit finite volume scheme based on a SIMPLE algorithm associated with the multiphase and cavitation model. The modified k-ε RNG turbulence model equipped with a modification of the turbulent viscosity was applied to overcome the turbulence closure problem. Numerical simulation of water flow over the hydrofoil equipped with the ACG shows that a low-pressure recirculation area is produced behind the ACG and artificially generates stationary cavitation bubbles. The location, shape, and size of this ACG are the crucial parameters in creating a proper control. Results show that the cavitation bubble is controlled well with a well-designed ACG.     

对一型潜器的水下振动响应分析（英文）

文章基于三维水弹性方法,分析了一型潜水器水下航行中的振动响应特性,通过求解干模态的广义坐标响应及对应的附连水质量,确定了干模态频率和湿谐振频率的对应关系。该文预报的水下响应曲线的峰值频率得到了水声试验测试结果的印证,说明了三维水弹性方法在求解水下结构振动响应问题上的有效性。文中最后对潜器尾部结构进行了改进,改进前后速度响应幅值曲线的比对表明,增加尾部纵桁结构的刚度对抑制潜器的尾部振动有明显的效果。     

一种基于声学定位/航位推算的水下导航定位方法

受环境影响,声学定位系统输出的位置信息波动较大,还会出现数据跳变或丢失现象,严重影响了水下载体的定位精度。针对此问题,提出一种基于声学定位/航位推算的组合导航方案,该方案在组合滤波前对声学定位系统输出数据可用性进行判断,进而选择不同的导航方式。采用计算机仿真和海试实验对研究方法进行了验证,结果表明,该方法能有效融合两种导航系统的优点,平滑声学定位系统数据的波动,且当声学定位系统输出异常时,水下载体短时间内还能保持较高的定位精度。     

一种基于航位推算的水下机器人导航算法

本文针对智能水下机器人(AUV)导航信息较少的特点,进行了基于航位推算的AUV导航系统研究.首先利用传感器信息进行了航位推算,然后建立了基于一阶时间相关函数的辛格模型,利用强跟踪卡尔曼滤波算法对推算结果进行了次最优估计,提高了系统的跟踪能力,改善了导航精度,同时对GPS数据进行了野值剔除.松花湖上的试验结果验证了算法的有效性.     

基于地形熵和ICCP算法的水下辅助导航组合方法研究

基于ICCP算法的水下地形辅助导航可以很好地弥补INS长期误差积累的缺点.但ICCP算法在INS初始误差较大情况下易发散,为解决这个问题,提出用地形熵和ICCP算法的组合方法,即先用地形熵算法做粗匹配来降低INS的初始误差,用ICCP算法进行精匹配得到最佳匹配位置,在粗匹配阶段采用动态门限法,在精匹配阶段引入滑动窗口,这样可提高组合算法的快速性.仿真结果表明,组合算法是正确的和有效的.     

一种自适应网格模糊交互多模型算法（英文）

This paper studies the algorithm of the adaptive grid and fuzzy interacting multiple model(AGFIMM) for maneuvering target tracking, while focusing on the problems of the fixed structure multiple model(FSMM) algorithm's cost-efficiency ratio being not high and the Markov transition probability of the interacting multiple model(IMM) algorithm being difficult to determine exactly. This algorithm realizes the adaptive model set by adaptive grid adjustment, and obtains each model matching degree in the model set by fuzzy logic inference. The simulation results show that the AGFIMM algorithm can effectively improve the accuracy and cost-efficiency ratio of the multiple model algorithm, and as a result is suitable for engineering applications.     

基于组合算法的水下地形辅助导航性能分析

针对目前水下地形辅助导航性能在单一算法下受多因素影响而无法得到最佳发挥的问题,采用双线性插值法制备了相应分辨率的水下数字地图,采用地形轮廓相关匹配(TERCOM)算法和基于直接概率准则的质点滤波(PMF)算法组成的组合匹配算法,较为全面地仿真分析了潜航器航速、测深误差、航向误差、航速误差、初始位置偏差和水下地形特征等诸多因素对导航性能的影响规律,对组合算法在复杂条件下的应用性能进行了剖析。仿真结果表明,在复杂条件下组合算法具有较强的稳定性和抗误差性,通过合理地选择应用参数,可有效降低匹配误差,提高导航性能,研究成果可为匹配算法在水下导航工程实践中的应用提供参考。     

基于少量测点的水下辐射噪声评估模型（英文）

文章针对复杂结构的水下辐射噪声实时评估问题,提出了一套基于工况传递路径法的线谱条件下理论模型,在确保辐射噪声评估准确性的同时,减少了传感器的使用数量。模型与工况分类相结合,提高了辐射噪声的评估精度。之后对该模型进行了数值仿真和湖上试验验证,结果表明,提出的模型简单有效。频段辐射噪声评估误差小于2 dB,多数线谱峰值频率处误差小于2.5 dB。该研究对船舶噪声评估具有参考意义。     

水下圆柱冲刷的时间演变（英文）

Temporal evolutions of scour at submerged circular cylinders were investigated. Flow visualization was carried out around the cylinders over plane, under developed and equilibrium scour holes. Video analysis technique was used to formulate the equations for determining the diameter of the horseshoe vortex around the submerged cylinders, which is also verified from the vector diagrams drawn using the velocity measurements. The scour process similar to live bed scour was noticed around the downstream cylinder. The diameter of the horseshoe vortex is found to depend on the diameter of respective cylinder, submergence ratio,spacing between the cylinders and skew angle. This formulation along with the dislodgement and transportation of a single sediment particle is further incorporated in the proposed model for determining the time variation of scour around the submerged cylinders. It is evident from the results that the upstream cylinder shelters the downstream cylinder and thereby reduces the scour at the downstream cylinder. Proposed model is further extended to incorporate the effect of non-uniformity of the sediment particles on the time variation of scour depth. The results indicate significant reduction of scour depth of around 6% and 35% for upstream and downstream cylinders respectively due to the formation of the armor layer. The model is also compared with the local scour component of field data around cylindrical bridge piers to establish the differences in the scour process around a partially submerged cylinder and fully submerged tandem and skewed cylinders.