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《舰船科学技术》2021,(13)
在声呐、雷达等设备的目标探测中,声源方位估计是需要解决的关键问题之一。针对水下传感器阵列接收信号的波达方向角(DOA)估计算法中,传统的BP神经网络算法会因网络参数不合理和层数过多导致过拟合的问题,以往通过粒子群算法(PSO)进行优化后,网络仍容易过早结束训练而导致性能不佳。为此,本文提出一种基于变分模态分解结合粒子群算法优化后的BP神经网络算法。首先对目标回波信号进行可变模态分解,对分解得到的各分量进行时频分析后叠加的谱图特征作为经粒子群算法优化后的BP神经网络算法的输入进行训练测试,以此来提高阵元接收目标回波的DOA估计精度。仿真实验结果表明,结合变分模态分解及粒子群算法优化的BP神经网络具有更好的识别效果和泛化能力,提高了DOA的估计精度。 相似文献
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电子海图上距离和真方位的计算精度 总被引:1,自引:0,他引:1
本文论述了计算电子海图上任意两点间的实地距离(大圆弧距离)和真方位的方法,给出了电子海图上点状物标的地理坐标的获取算法,对电子海图数据库中物标的地理坐标进行了误差估计,运用数学分析方法对距离和真方位的计算精度进行了估算。 相似文献
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对纯方位跟踪问题进行了描述,通过建立模型,设计求解算法,提出了一种解纯方位跟踪问题的非线性最小二乘方法,并将它与解纯方位跟踪问题的线性最小二乘方法进行了比较与仿真分析。仿真结果表明,非线性最小二乘方法具有较高的估计精度,是一种有效的算法,对潜艇实施隐蔽探测与跟踪具有重要意义。 相似文献
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通过设计适当的聚焦(Focusing)矩阵将信号各个频带的能量聚焦到同一个参考频率上,对各子带的阵列相关矩阵进行频域平均,得到一个信号子空间,然后使用窄带高分辨算法进行方位估计。本文将该算法应用于水下宽带相干源方位估计,实现了高分辨率。 相似文献
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《船舶与海洋工程学报》2014,(2)
正In the paper"Influence of Fouling Assemblage on the Corrosion Behaviour of Mild Steel in the Coastal Waters of The Gulf of Mannar,India"in Vol.12,No.4,Page:509,References were lost,and the two authors’biographies were identical.The correct text is shown below.We apologize to the authors and our readers for any inconvenience caused by the errors. 相似文献
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《船舶与海洋工程学报》2014,(4)
正St.John's,Newfoundland,Canada,May 31-June 5,2015 OMAE2015 is the ideal forum for researchers,engineers,managers,technicians and students from the scientific and industrial communities from around the world to: meet and present advances in technology and its scientific support; 相似文献
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联合作战计划和执行系统 总被引:2,自引:1,他引:1
全球指挥控制系统(GCCS)实施当前美国海军网络中心战信息基础设施的联合计划网络。联合作战计划和执行系统(JOPES)支持GCCS实现联合计划。JOPES有两类计划:时间不限的精密预案计划生成作战计划、方案计划或职能计划;时间敏感的危机行动计划生成作战命令或战役方案。前者在和平时期创建的作战计划是后者的计划基础,加速应付危机的能力。 相似文献
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In terms of equal sailing distances, where is the inflexion when ships depart from ports in the Asian Continent to New York via Suez and/or Panama?
The answer is China South Port Group (Hong Kong, Shenzhen and Guangzhou). 相似文献
The answer is China South Port Group (Hong Kong, Shenzhen and Guangzhou). 相似文献
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Recent measurements of wave induced hull strain and flexure in RN warships are presented together with the derivation of the current design criteria for extreme hull girder bending loads. The history of the development of the shipboard instrumentation used is given and recent developments to improve the quality and ease of analysis of the data are described. An unexpectedly high transverse asymmetry in the longitudinal strains measured in destroyers is shown to be the result of a combination of vertical and lateral bending in oblique seas. Finally recent theoretical comparisons between the loading of Deep-Vee hulls and conventional UK rounded bilge hulls are presented which demonstrate the higher loading experienced by this type of hull form. 相似文献
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桥梁防撞设施物理模型试验 总被引:1,自引:0,他引:1
物理模型试验是预报防撞设施所受撞击力及优化设计方案的主要方法之一。结合杭州湾大桥柔性防撞设施及东海大桥独立式防撞体设计方案,阐述了船—防撞体撞击试验的基本原理、方法、试验方案及相关试验结果。提出了柔性防撞系统的优化方案。试验结果表明,该方案经济有效,可供预报类似桥梁防撞设施撞击力时参考。 相似文献
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印尼某电厂项目码头水工建筑物包括码头、防波堤和护岸等主要组成部分。在该项目水工建筑物的设计过程中,综合考虑当地的自然条件、施工能力和材料来源等因素,不断优化结构选型和结构断面。根据不同使用要求,护岸分别采用直立式和斜坡式2种结构型式,推荐的设计方案节省投资、施工方便,可供同类工程设计参考。 相似文献
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Gunnar Alexandersson Staffan Hultén Frode Longva 《Research in Transportation Economics》2010,29(1):212-218
Despite the many socio-economic similarities between Sweden and Norway, differences in jurisdiction, organisation, cooperation, and financing of long-distance passenger train and coach services have led to the development of four distinctively different ways of serving the markets. This paper describes how the train and coach markets have developed in the two countries, with emphasis on regulatory and industrial structure and a couple of performance variables.Looking at passenger rail, both countries separated infrastructure from operation over a decade ago. However, while Norwegian rail is characterised by an almost monopoly supplier, rail services in Sweden are partly decentralised to the responsibility of county authorities and are widely subjected to competitive tendering. The rest of the network is about to be opened up for on-the-track competition. Swedish Rail (SJ) has spent the last decades consolidating its core business (passenger rail) and sold out its other businesses. In contrast, the Norwegian state rail (NSB) has expanded its business to become a major bus operator and property owner, with extensions also into the Swedish market.The coach industry was more recently deregulated in both countries. The Swedish coach market is dominated by privately owned companies operating services to and from Stockholm. In Norway, state-owned NSB is a major coach operator on medium distance routes, and is also the largest partner of Nor-Way Bussekspress which totally dominates long-distance coach services. Further, the Norwegian coach market is characterised by cross-ownership and cooperation which has enabled an extensive route network which covers most of Norway.We find distinct differences in achievements in the two modes and in the two countries. Swedish rail services have succeeded in winning market shares and in renewing and developing both infrastructure and service levels to a greater extent than the Norwegian model. On the other hand, the Norwegian coach market seems to be more developed and efficient compared to its Swedish counterpart.The paper concludes with a discussion on the possible links between the different approaches and the performance observed, with the aim to stimulate further and more detailed research on some important issues. 相似文献