Underwater Terrain-Aided Navigation Based on Multibeam Bathymetric Sonar Images

在水下帮助地面的航行被用来补充采用由的传统的惯性的航行自治在水下车辆在过长的使命期间。它能由与一张数字地面地图匹配即时深度数据提供固定评价。这研究介绍使用处理技术在的图象的概念在水下地面匹配过程。一幅图象的一张传统的灰阶的直方图被加入在象素与空间信息充实。边角落象素然后被定义并且过去常构造一张边角落直方图，扫描数字地面地图并且由寻找关联山峰估计车辆的改正作为一个模板采用它。模拟被执行调查建议方法的坚韧性，特别地在与它到背景噪音，即时图象的规模，和车辆的旅行方向的敏感的关系。在 1 m 2/pixel, 的一个图象决定，本地化的精确性是超过 10 米。

ANALYSIS OF BATHYMETRIC FEATURES USING SARIMAGE: AN EXAMPLE FROM THE SOUTHERN NORTH SEA

This paper presents the authors ’ simulation model of the bathymetric features on SAR image and their inversion model for detecting bathymetric features by SAR image. A function G proportional to the radar backscatter cross section σ0 is defined to simulate the radar image gray tone level based on Yuan (1997). The inversion method is the minimum deviation solution proposed by Jin and Yuan (1997b). Tests with actual data of the Seasat SAR image and the sea chart of the southern North Sea showed that the models could simulate and detect the basic bathymetric features.

Reconstruction of large complex sand-wave bathymetry with adaptive partitioning combining satellite imagery and sparse multi-beam data

Shallow marine sand waves are formed on the seabed and are widely distributed within tidal environments.However,the use of multibeam echo sounding(MBES)is costly to obtain the bathymetric mapping of large complex sand waves.Therefore,we propose a new method that employs a combination of multiangle sun glint images and sparse MBES data to achieve comprehensive bathymetric mapping of large and complex sand waves.This method involves estimating sea surface roughness,automatically extracting sand-wave crests,conducting adaptive subregion partitioning,estimating the water depth at auxiliary points,and generating digital bathymetric models.The method was employed in a case study of sand waves on the Taiwan Bank.Bathymetric mapping was implemented for large complex sand waves over an area spanning approximately 350 km~2 using multiangle sun glint images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer and MBE S data.The results show that mapped and measured water depths were well-matched;the root-mean-square error of water depths was 1.77 m,and the relative error was 5.03%.These findings show that bathymetric mapping of large complex sand waves can be effectively conducted using the new method,and as such,the workload of MBES is reduced and efficiency is improved.

A True-Time-Delay Array Architecture for Wideband Multi-Beam Tracking

The true-time delay(TTD)units are critical for solving beam squint and frequency selective fading inWideband Large-Scale Antenna Systems(LSASs).In this work,we propose a TTD array architecture for wideband multi-beam tracking that eliminates the beam squint phenomenon and filters out interference signals by applying a spatial filter and time delay estimations(TDEs).The paper presents a novel approach to spatial filter design by introducing a transformation matrix that can optimize the beam response in a specific direction and at a specific frequency.Using the variable fractional delay(VFD)filters,we propose a TDE algorithm with a Newton-Raphson iteration update process that corrects the arrival time delay difference between sensors.Simulations and examples have demonstrated that the proposed architecture can achieve beam tracking within 10 ms at the low signalto-noise ratio(SNR)and demodulation loss is less than 0.5 dB in wideband multi-beam scenarios.

基于不同遥感影像的无控水深反演精度比较

为检验无控制点的遥感水深反演在不同空间分辨率遥感影像下的适用性和测深精度,介绍并推导了无实测控制点的双波段对数线性分析算法,基于空间分辨率为2 m的WorldView-2影像、10 m的Sentinel-2影像和16 m的GF-1 WFV4影像,以赵述岛和甘泉岛为研究区域,反演水深值,并将反演结果与实测水深进行对比及精度评价分析。结果显示:两个研究区域WorldView-2影像的无实测控制点水深反演模型精度最高,Sentinel-2影像的水深反演精度较好,GF-1 WFV4影像的水深反演精度最低,且遥感影像的空间分辨率、辐射分辨率和无控制点几何定位精度对无实测控制点的双波段对数线性分析模型的水深反演结果存在影响。

遥感水深反演海道测量业务化应用中的评估与思考

水深是海道测量最重要的地理要素,反映海底地貌形态和航区通航能力,在海道测量中占有重要的地位,遥感水深反演(SDB)对于补充传统声学测深系统效率不足具有重要意义。本文通过对现有研究总结,从实地因素、影像因素和反演方法3个维度分析了反演考量的要素,对照海道测量精度要求和业务化需求两个维度对水深反演适用性进行了评估。结果表明,精度方面,SDB水平精度已经满足要求,大部分多光谱反演相对垂直精度约达20%,但受水体浑浊程度影响较大,距海道测量业务化应用尚有不足,海底覆盖方面已经有了很好的实践。最后,从不确定性可控性、反演模型外推和多源数据同化方面分析了SDB应用所面临的问题,并给出了一些思考和建议。

ICESat-2水深提取方法及其反演应用

相比于传统水深测量方法,结合主动激光卫星ICESat-2数据与被动光学遥感影像的主被动融合水深反演方法具有低成本、覆盖面积广、不受地域限制、无需地面实测数据等优点.研究选取澳大利亚大堡礁中部的John Brewer Reef和南部的Fitzroy Reef为实验区,开展主被动融合水深反演实验.针对ICESat-2光子点群信噪比低、光子点水深信息提取和改正难的问题,本文提出基于光子点群高斯分布特征的海面光子点群提取方法和基于深度自适应DBSCAN的海底光子点群提取方法,并顾及海面倾斜引起的入射角偏移,改进了Parrish水体折射改正几何模型.实验表明,基于光子点群高斯分布特征的海面光子点群提取方法和基于深度自适应DBSCAN的海底光子点群提取方法可以高效准确地提取出有效的海面、海底光子点群;经过地球物理改正和基于改进模型的水体折射改正后,水深变浅,且改正项与改正前水深呈线性关系,线性系数约为-0.2550.实验将提取并改正后的ICESat-2光子点水深与经大气校正、耀斑校正、空间域滤波等预处理后的Sentinel-2影像进行空间匹配构建水深反演样本集,并利用单波段模型(SB)、比值模型(BR)、Lyzenga多项式模型(LP)、二次多项式模型(QP)、三次多项式模型(CP)、支持向量回归模型(SVR)、多层感知器模型(MLP)、随机森林回归模型(RF)等水深反演模型对实验区全域水深进行反演.通过对比分析多种水深反演模型在不同地理区域和ICESat-2水深样本分布条件下的表现,研究为不同场景下的主被动融合水深反演策略提供了一定的科学依据.

基于测深侧扫声呐的DOA估计算法研究

针对测深侧扫声呐进行波达方向(Direction of Arrival,DOA)估计时会受到阵元幅度、相位误差及低信噪比影响的问题,提出一种改进的波束域加权子空间拟合算法。首先,采用总体最小二乘-旋转不变子空间算法进行回波方向预估计;其次,将连续线阵划分为多个子阵,并将各个子阵在预估计方向做加权波束形成;再次,采用加权子空间拟合(Weighted Subspace Fitting,WSF)算法构造代价函数;最后,采用阻尼牛顿法求解得到高精度的DOA估计结果。仿真结果表明,文中所提算法在阵元出现幅度相位误差条件下的角度估计均方误差相对于WSF算法减少了约0.03°。海试数据分析结果表明,文中所提算法的测深点均方误差整体优于WSF算法,其相对测深精度提高了约9.8个百分点。以上分析结果表明,文中所提算法整体优于WSF算法,可以实现在阵元幅度相位误差及低信噪比情况下的高精度DOA估计。

多种混合格式CAD水深数据的智能识别提取

在CAD水深测量成果图中,水深往往以分离的文本方式标注,其整数、小数、小数点、负号等各部分相互分离且形式多样,这给水深信息提取工作带来了很大的困难。本文基于空间数据关联规则挖掘思想,建立空间布局拓扑表,采用人工神经网络学习和分类识别方法,智能识别和提取水深数据。此方法无需预先指定格式及其他参数,创新性实现了多种混合格式水深数据的自动化、智能化识别提取,且准确率高、速度快,在工程领域具有一定应用前景和推广价值。

基于多源数据融合的澎湖水道数字水深模型构建

为了在澎湖水道生成一个高质量的数字水深模型(Digital Bathymetric Model, DBM),分析了不同DBM在不同子区域之间的差异,利用自适应分区域空间加权融合方法构建了一个新的DBM。结果表明,在当前使用最为广泛的DBMs中,SRTM30_PLUS、GEBCO_2021、SRTM15_PLUS这3种DBM质量较好,均方根误差(Root Mean Squared Error, RMSE)为7.931~8.016 m,而ETOPO1、GEBCO_2014和TOPO V19.1质量较差,RMSE为11.439~20.105 m;利用本文研究方法所构建的澎湖水道数字水深模型的RMSE为6.970 m,其精度比GEBCO_2021、SRTM30_PLUS和SRTM15_PLUS模型分别高12%、13%和12%,利用本研究方法所构建的DBM恢复了高精度水深点,保留了地形细节信息。研究结果可为从多个数据集中及时重建和更新大规模海底地形提供参考,并推广应用于其他环境和区域中。

Near-Field Beam Training for Holographic MIMO Communications: Typical Methods, Challenges and Future Directions

Holographic multiple-input multiple-output(HMIMO)has become an emerging technology for achieving ultra-high frequency spectral efficiency and spatial resolution in future wireless systems.The increasing antenna aperture leads to a more significant characterization of the spherical wavefront in near-field communications in HMIMO scenarios.Beam training as a key technique for wireless communication is worth exploring in this near-field scenario.Compared with the widely researched far-field beam training,the increased dimensionality of the search space for near-field beam training poses a challenge to the complexity and accuracy of the proposed algorithm.In this paper,we introduce several typical near-field beam training methods:exhaustive beam training,hierarchical beam training,and multi-beam training that includes equal interval multi-beam training and hash multi-beam training.The performances of these methods are compared through simulation analysis,and their effectiveness is verified on the hardware testbed as well.Additionally,we provide application scenarios,research challenges,and potential future research directions for near-field beam training.

基于全球海域多波束测深数据构建DBM与Web服务

为解决全球海域多波束测深数据查询使用不便的问题,通过数据分块实现海量数据处理,使用逐点插值算法构建数字水深模型,将晕渲图与数字水深模型组合构建可视化查询服务,实现基于浏览器查看水深数据和查询水深值等功能。对已有的全球海域多波束测深数据进行了处理,结果表明该方法对海量数据有着很好的承载能力,构建的数字水深模型能够反映测深点分布情况,Web查询服务响应迅速;同时该方法基于常用GIS软件处理数据,可操作性强,可用于海量多波束测深数据管理。

集成化水深测量装置研发及应用

为更好地解决码头前沿及其下方、浅水区等船舶行驶受限区域的水深测量难的问题,研制了一种新型集成化测深装置。该装置采用一体化设计,集成了电源模块、测深模块、水文参数测量模块和专业测深软件等。以传统单波束测深仪的测量数据为参照,对集成化测深装置的吃水深度、声速、内符合和外符合方面的测量数据进行分析和评价。结果证明:集成化测深装置的测量准确性和性能稳定性较好,可实时高效地获取码头前沿及其下方、浅水区等船舶行驶受限区域的高精度水深数据。

多波束测深仪在超浅水域的应用分析

在对沿海虾蟹养殖坑塘进行回收时需进行坑塘回填,一般通过水下测量获取,获得坑塘水底的水深值。人工划船辅以RTK的传统测量方法效率低且人工投入大、单波束测深仪又存在覆盖范围窄和测量精度低的缺点,无法满足短平快的日常测绘要求。多波束测深技术的不断发展和成熟给水下测量方法提升带来可能。经分析,使用多波束测深仪在坑塘等超浅水域测量中有明显效果,因其具有测量范围大、测量速度快、测量精度和效率高的优点,特别适合进行大面积的水下探测。并与传统方法的测量精度进行比较,得出多波束测深仪在超浅水域中的测量可满足日常沿海虾蟹养殖坑塘的测绘要求。

潮位观测对水深测量精度的影响分析

在港口及其配套设施建设的勘察设计阶段以及港口航道的正常运行维护阶段,港口航道、锚地、港池等区域的水深测量都显得十分重要。获取详细精确的水深测量数据可以为港口的设计及运营维护提供第一手资料,也是保证来往船只安全正常航行的必要手段。根据水深测量项目实施过程中积累的观测数据,进行了潮位观测时间对水深测量精度的影响分析的研究。后期在进行水深测量时,可以按照现场实际情况利用本课题的研究成果适当减少海上临时验潮站的观测时间,节约施工成本,提高作业效率。

3D Modal Solution for Tidally Induced Lagrangian Residual Velocity with Variations in Eddy Viscosity and Bathymetry in a Narrow Model Bay

In this study, we examine the results obtained by the Finite-volume Coastal Ocean Circulation Model(FVCOM) regarding the effects of eddy viscosity and bathymetry on the three-dimensional(3 D) Lagrangian residual velocity(LRV) in a narrow bay. The results are cast in terms of two nondimensional numbers: the ratio of friction to local acceleration(δ) and the ratio of the minimum depth over shoals to the maximum depth in the channel(ε). The ratio δ depends on the eddy viscosity and mean depth. For a given eddy viscosity, when ε > 0.5, the along-estuary LRV tends to be vertically sheared and when ε < 0.5, the exchange is laterally sheared. When ε << 1, the structure of the 3 D, depth-integrated, and breadth-averaged LRV changes only slightly as δ increases. For ε values between 0.33 and 0.5, the structure of the 3 D LRV is mainly laterally sheared. In the same ε range, the 3 D and depth-integrated LRV exhibit reversed structures from high to low δ values. In addition, the breadth-averaged LRV weakens the typical twolayered circulation when δ decreases. When ε is 1, the two-layered vertical structure reverses direction, and a three-layered vertical structure develops in the outer bay as δ decreases.

Joint Optimization of Satisfaction Index and Spectrum Efficiency with Cache Restricted for Resource Allocation in Multi-Beam Satellite Systems

Dynamic resource allocation(DRA) is a key technology to improve system performances in GEO multi-beam satellite systems. And, since the cache resource on the satellite is very valuable and limited, DRA problem under restricted cache resources is also an important issue to be studied. This paper mainly investigates the DRA problem of carrier resources under certain cache constraints. What's more, with the aim to satisfy all users' traffic demands as more as possible, and to maximize the utilization of the bandwidth, we formulate a multi-objective optimization problem(MOP) where the satisfaction index and the spectrum efficiency are jointly optimized. A modified strategy SA-NSGAII which combines simulated annealing(SA) and non-dominated sorted genetic algorithm-II(NSGAII) is proposed to approximate the Pareto solution to this MOP problem. Simulation results show the effectiveness of the proposed algorithm in terms of satisfaction index, spectrum efficiency, occupied cache, and etc.

User-Level Scheduling and Resource Allocation for Multi-Beam Satellite Systems with Full Frequency Reuse

Multi-beam satellite communication systems can improve the resource utilization and system capacity effectively.However,the inter-beam interference,especially for the satellite system with full frequency reuse,will degrade the system performance greatly due to the characteristics of multi-beam satellite antennas.In this article,the user scheduling and resource allocation of a multi-beam satellite system with full frequency reuse are jointly studied,in which all beams can use the full bandwidth.With the strong inter-beam interference,we aim to minimize the system latency experienced by the users during the process of data downloading.To solve this problem,deep reinforcement learning is used to schedule users and allocate bandwidth and power resources to mitigate the inter-beam interference.The simulation results are compared with other reference algorithms to verify the effectiveness of the proposed algorithm.

Numerical investigation of multi-beam laser heterodyne measurement with ultra-precision for linear expansion coefficient of metal based on oscillating mirror modulation

This paper proposes a novel method of multi-beam laser heterodyne measurement for metal linear expansion coefficient. Based on the Doppler effect and heterodyne technology, the information is loaded of length variation to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, this method can obtain many values of length variation caused by temperature variation after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, it can obtain length variation accurately, and eventually obtain the value of linear expansion coefficient of metal by the calculation. This novel method is used to simulate measurement for linear expansion coefficient of metal rod under different temperatures by MATLAB, the obtained result shows that the relative measurement error of this method is just 0.4%.

Handover initiation performance of a new multi-cell cellular configuration with a developed base-station multi-beam antenna

A new multi-cell cellular configuration networks is provided for analysis of handover initiation probability, which is based on multi-beam base-station antenna splitting in the elevation-radiating plane. The sum of the received signal power in the mobile station, including both desired and interference signal power, has been introduced into the handover initiation algorithm. Along with the idea, we present three models of handover initiation algorithm with the shadowing process of Gaussian distribution. The formulation of handover initiation probability of those algorithms is also analyzed. The validity of the presented models has been checked through the comparison with simulation results. The results present the performance characteristics of handover initiation vary with cluster number and base-station antenna elevation angle.