一种基于小波去噪的脉冲噪声抑制方法

小波去噪是近年来兴起的信号处理领域中的高新技术,而目前许多研究方法都是以高斯噪声为背景的.在小波阈值去噪的基础上,将伪随机m序列引入小波去噪方法中,可有效去高斯噪声中掺杂的脉冲噪声.     

基于小波阈值法和LMS自适应滤波法的舰船去噪方法

在海上行驶过程中,为确保安全稳定航行,有必要高度重视舰船去噪的重要性。其中,在舰船去噪过程中,将信噪比增益当做小波基函数的一个重要参数进行研究,可以将改进后的小波阈值算法应用到舰船的背景信号去噪算法中,进而改善去噪的效果。而LMS自适应滤波器则能够结合环境改变对滤波器的系数进行自动调整,结构相对简单且运算量不大,容易满足硬件需求,所以也在噪声对消与信号预测、增强等诸多领域中得到广泛应用。在舰船去噪中,将小波阈值去噪方法与LMS自适应滤波算法应用于其中具有一定的可行性,值得展开进一步研究与探讨。     

基于小波分析的跌落零件监测系统

小波是当前最强有力的分析工具之一,研究小波分析具有重要的理论意义和实用价值。本文旨在进一步拓宽小波的应用范围,主要研究小波分析在大型设备中跌落零件监测系统的应用,基于传统的阈值去噪方法,结合它们的优缺点之后,为了提高去噪质量的目的,提出了一种改进方案。该改进方案克服了传统阈值去噪方法的缺陷,仿真试验证实了该改进方案的有效性和优越性。     

平移不变小波变换在消除电路噪声中的应用

为了提高火控测试系统测试结果的精度与可信度,去除对测试系统在采集火控系统信号时混入的噪声是十分必要的.通过对某型火控系统在动态测试时采集的信号的研究,针对传统小波阈值去噪处理方法中因非一致降样取样而产生Pseudo-Gibbs现象,结合已有改进阈值法的优点,提出一种新型阈值函数代替传统软硬阈值函数,采用平移不变小波变换对采集的信号进行去噪处理,以提升去噪的效果.仿真结果表明,该方法能进一步减少均方误差,提高信噪比,使去噪后信号更好地逼近真实信号,具有一定的工程实用性.     

基于自适应小波阈值与曲波变换的SAR图像去噪

目前,国内外都使用合成孔径雷达(Synthetic Aperture Radar, SAR)做为海上小目标检测应用的重要技术手段,然而海上小目标的检测存在SAR图像不够清晰的问题。针对该问题,设计将自适应小波阈值与曲波变换去噪方法相结合,对图像进行去噪处理。该融合算法不仅能够解决传统小波阈值去噪"一刀切"造成的过度去噪以及只能对"点奇异"特征函数的最优逼近,而且优化曲波变换只对"线奇异"特征函数最优逼近的问题。通过一系列的量化指标和视觉效果进行去噪性能比较可知:该方法背景杂波更加平滑、目标与背景对比度更高。     

小波变换在直升机高度表信号去噪中的应用

介绍了小波理论知识,分析了阈值去噪法的特点。并针对小波阈值萎缩去噪方法的阈值函数选取问题进行了详细讨论,然后对常用的五种阈值选择规则进行了仿真试验。     

基于小波能量熵的水下目标磁场信号去噪

本文提出了基于小波能量熵的水下目标磁场信号去噪方法,通过对信号进行小波分解,计算各层目标信号和背景噪声的小波系数能量熵,利用信号在不同的分解尺度上具有不同的小波熵,自适应地确定高频系数的阈值,利用经过处理后的小波系数进行小波反变换,实现对水下目标磁场信号的去噪.仿真试验结果表明,该方法能有效去除背景噪声,检测出目标磁场...     

基于经验模式分解的滤波去噪算法

经验模式分解法被认为是非线性、非平稳数据处理方法的新进展.其最大优点是根据信号本身的特性自适应地产生合适的模态函数,这些模态函数能很好地反映信号在任何时间局部的频率特征,克服了小波变换中要选取合适小波基的困难.基于经验模式分解的分解特性,本文提出了一种新的阈值去噪方法,通过事先建立的经验阈值,根据自适应方法对噪声进行去除,然后对去除的噪声进行随机采样后加入到去噪信号中重新滤波,通过反复滤波迭代进行噪声的去除.实验结果证明了本方法与小波相比具有自身独特的优势.     

一种旋转机械振动信号小波去噪方法

针对旋转机械的非平稳振动信号难以用传统方法处理的问题,本文讨论了小波方法在旋转机械振动信号去噪中的应用。针对旋转机械故障信号的特点,提出阈值去噪和模极大值相结合的小波去噪方法对振动信号进行处理,并利用多种指标对去噪后信号做出全而客观的评价。实验结果表明该方法可以有效的提高故障信号信噪比,有利于提高后期故障诊断的准确率。     

小波分析在信号消噪中的应用研究

小波分析具有在频率域的多分辨能力,已广泛用于信号和图像的消噪中。在引入小波阈值去噪方法的基础上,提出了一种新的阈值函数。经过信号仿真验证,这种新的阈值函数取得了较好的消噪效果,克服了采用传统的软、硬阈值函数去噪的不足。     

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。