基于小波变换和神经网络的数字调制识别技术

本文讨论了基于小波变换的几种常用调制制式(BASK、4ASK、2FSK、4FSK、QPSK、8PSK、16QAM)的神经网络识别问题,利用小波变换提取信号特征,再通过BP神经网络来分类,有机结合了小波变换良好的时频局部特性和神经网络的自学习、自适应性。在加性高斯自噪声条件下通过仿真研究了该识别方法的性能。     

基于分集接收技术的岸海短波通信系统研究

论文针对岸海实际通信环境,结合短波信道特点,提出了一种基于信号特征识别的智能化信道分集接收技术,基于该技术构建岸海短波通信系统,并通过实际信道对通信效果进行了验证,具有一定的推广应用价值。     

直扩通信系统中DQPSK解调算法的改进研究

文章在阐述DQPSK调制算法原理和实现方法的基础上,在解调器采用旋转法解差分编码,并通过鉴相器,产生控制载波捕获与跟踪用的信号,克服了载波相位模糊度问题、数字信号可能极性倒置等问题。基于DQPSK调制改进算法的分析,利用Matlab对该算法进行仿真,结果表明,所述改进算法基本满足通信要求。     

舰船短波通信网络微弱信号自适应增强算法设计

受到短波通信波段子带分布数量较大的影响,传统信号增强算法难以适应不同频域信号的增强系数调节,导致不同子带频域空间下的信号强度与微弱信号点适应系数出现偏差,难以达到增强预期效果。为此,设计了新的舰船短波通信网络微弱信号自适应增强算法。结合短波通信特点优化卫星短波传输过程的共振信号,然后根据传统信道的子代分布特点优化其信噪比,最后完成对子带信号的自适应优化计算,从而实现对不同子带频域空间中带微弱信号的自适应增强计算。实验结果表明:在提升短波信号适应度的角度上,本文算法具有信号适应性强、微弱信号调制增强效果好的优点。     

短波自适应通信网络多址链接算法研究

传统网络通信链接算法在对短波链接计算过程中,受到算法连接协议的限制与算法对短波信号的适用性较差,导致多址链接抗干扰性下降,无法稳定分配链接地址。因此,提出短波自适应通信网络多址链接算法研究。根据短波信号特性,引入短波正交阵列策略,对短波通信数据进行链接优化计算,提升数据的抗干扰性;接着,通过引入多址时隙链接算法,对数据链接进行时间化地址分配,实现链接分配的自适应;最后,通过对比仿真实验,证明提出的算法具有实用性强、抗干扰性强、稳定性好的特点。     

双差波束约束下舰艇短波自适应通信抗干扰分析

由于利用原有方法进行舰艇短波自适应通信抗干扰时,受到信号正交空间噪声的影响而无法对短波发射通道误差进行校准,在天线频率为220 MHz,430 MHz时,存在辐射面积较低的问题,因此提出一种双差波束约束下舰艇短波自适应通信抗干扰方法。首先对舰艇短波自适应通信中的短波发射通道幅相误差进行校准,并通过双差波束算法处理舰艇短波自适应通信发射超分辨,最后通过短波天线自适应通信抗干扰阵列,实现舰艇短波自适应通信抗干扰,该阵列由自适应通信处理器、形成方向图网络以及阵列天线构成。为了证明设计方法在2种频率下的辐射面积较大,将原有方法作为对比实验方法进行对比实验,实验结果证明该方法在2种频率下的辐射面积都更大,实现了性能突破。     

8PSK信号在衰落信道下信噪比盲估计算法

针对传统信噪比估计算法要求利用训练序列或一帧数据范围内信道系数恒定等问题,文章提出了一种8PSK信号在衰落信道下盲信噪比估计算法。该算法利用信道系数的统计特性,理论分析信噪比与接收信号的数值关系,采用多项式数据拟合和观测量归一化处理的方式,推导信噪比与接收信号解析式。数值仿真表明该算法在0～8dB范围内,可取得良好的信噪比估计效果。     

自适应信号处理在海面通信信号处理中的应用

在海面无线通信系统中,短波通信技术由于其高速的数据传输特性得到了广泛应用。但是一方面由于海面噪声引起的码间干扰由此造成的信号畸变,另一方面海面多径信道在短波通信中引起的实际无线信道系数的多变性均要求通信系统中的均衡滤波器能快速自适应进行修正。本文在研究现有自适应信号处理算法的基础上,提出一种新的基于异构补偿的自适应反馈滤波算法。最后利用此方法对短波无线通信系统进行了仿真,结果表明,此算法具有良好的稳定性及收敛性。     

一种短波差分跳频信号检测方法

短波差分跳频通信跳速高、信息速率高、抗干扰性能好,具有良好的应用前景。低信噪比下跳频信号的检测是短波差分跳频的关键技术之一,为提高低信噪比下短波差分跳频信号的检测性能,提出了一种基于切片瞬时四阶矩相位信息的跳频信号检测方法。理论分析和仿真结果表明,该方法对噪声具有较好的鲁棒性,在低信噪比情况下,检测性能较传统的基于瞬时相关函数的方法有明显改善,而计算量相当,具有实际应用价值。     

海上短波通信系统链路优化和功率控制技术

短波通信是海上船舶常用的一种通信形式,由于短波信号的易衰减等固有特性,进行海上短波通信的链路优化和功率控制,对于改善海上短波通信的信号精度、功率特性有重要意义。本文结合遗传算法和短波通信的基本特性,开发一种新型船舶短波通信链路功率控制技术,并进行了海上短波通信信号质量的仿真测试,取得较好的效果。     

Errata

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.     

Journal of Marine Science and Application 2014 Sum. Contents

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第34届海洋、离岸及极地工程国际会议(英文)

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;     

联合作战计划和执行系统

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。     

Eastbound or westbound ?

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）.     

Recent progress on wave induced loading measurements in warships

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.     

桥梁防撞设施物理模型试验

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。     

印尼某电厂码头水工建筑物设计

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。     

Impact of regulation on the performances of long-distance transport services: A comparison of the different approaches in Sweden and Norway

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.     

开放式数据挖掘系统模型

目前国内已经出现了少量的数据挖掘相关产品。国内数据挖掘软件无论从数量还是质量上比较，都与国外软件存在着较大的差距。随着数据仓库技术的普及，数据挖掘应用的需求越来越强烈，如何缩短这种差距，研发数据挖掘软件产品成为国内业界的一个重要问题。通过引用目前国际通用数据挖掘标准技术来构建开放式的数据挖掘系统模型，该系统模型从可扩展性、可重用性、易用性等方面得到了加强。