基于复数无迹卡尔曼滤波的电力系统频率和谐波估计

针对噪声干扰条件下传统的扩展卡尔曼滤波方法在电力系统频率和谐波估计精度问题,本文提出了基于复数无迹卡尔曼滤波的频率和谐波估计方法.利用欧拉公式,对电力系统信号进行适当变换,获得电力系统信号复数状态空间模型,实现了系统信号频率和谐波估计.为了验证噪声干扰条件下本文方法参数估计有效性,通过在系统信号中增加不同信噪比噪声干扰,分别利用本文方法和通用扩展卡尔曼滤波方法对参数进行估计.结果表明,在噪声干扰条件下,本文方法的估计精度优于通用扩展卡尔曼滤波方法,这表明本文方法更适于强噪声干扰条件下的系统信号频率和谐波估计.     

网式过滤器的压降计算和试验研究

本文着重对网式过滤器的压降计算方法进行了计算介绍.过滤器的压降计算采用滤器流道压降数学仿真计算和滤网压降数值计算相结合的方法.同时采用滤器压降试验验证方法与理论计算方法进行对比分析,对比的结果显示本文采用的理论计算方法与实际试验测试结果基本吻合.     

海船闸气幕防咸设计

为指导船闸气幕防咸设计,本文将经典Abraham方法和Keetels数据进行比较.结果发现,Abraham方法偏保守.基于Keetels数据,本文提出一种新的半经验公式,以获得更准确的供气量.     

虚拟样机技术在气垫船推进系统特性研究中的应用

由于气垫船的结构特点,传统的研究方法不适于气垫船推进系统特性研究.本文将现代虚拟样机技术引入气垫船推进系统特性研究中,对气垫船船体和轴系建模及船体-推进系统的耦合方法进行了比较研究.并应用本文提出研究方法,对某型气垫船推进轴系进行了动态支承力的仿真研究.     

结构冲击试验的校准计算

非线性有限元方法日益广泛地应用于结构冲击损伤的数值模拟计算,其可靠性和精度是值得关注的问题.本文为国际船舶结构大会(ISSC)对于本专题合作研究的部分结果.本文用超大型油船船侧结构碰撞大尺度模型试验的测量结果,验证非线性有限元方法及其代表性程序MSC.Dytran的计算效果.通过准静态和动态试验资料与计算结果的比较,指出非线性有限元方法在钢结构冲击(碰撞)计算中的有效性,同时指出正确实施计算过程,特别是有限元网格密度对于计算结果精度的重要性.对于结构在同一位置经受多次冲击的累积损伤计算,本文提出了一种非常简单但准确有效的模拟计算方法.     

潜艇横向刚性构架区域应力计算解析方法

本文对框架肋骨及平面舱壁船体结点区域的应力进行理论求解,考虑了内、外框架肋骨和结点区域嵌入厚板,以及厚、薄板连接处由于中曲面不一致引起的附加力矩和邻近普通肋骨对框架肋骨及平面舱壁纵向弯曲的影响.应用本文的计算方法、现行计算方法和有限元方法进行实际结构结点应力的比较计算,结果表明本文的计算方法比现行的计算方法更合理、更全面.     

二维水翼流体力学反问题的数值模拟

水翼(机翼)的反设计一直是人们研究的热门课题,本文对定常反问题进行了研究.将翼型NACA2412作为计算对象.首先给出翼型的下半部形状,以及上表面的从正问题中计算出来的速度分布.在变分原理的基础上,用有限元方法对水翼进行了数值计算.结果表明,本文理论正确,方法可行.     

基于叠加训练序列的稀疏水声OFDM信道估计(英文)

针对稀疏多径的水声OFDM信道,提出了基于叠加训练序列的信道估计方法,能够提高带宽传输效率.在发送端的信息序列中叠加一个低功率的周期性训练序列,在不占用额外的信号带宽的情况下估计信道参数,未知的信息序列会对叠加训练序列的信道估计方法产生干扰,在本文中采用迭代方法提高估计性能.水声信道具有延时时间长,信道稀疏的特点,本文采用匹配跟踪的方法估计信道非零系数的位置,降低加性白噪声对信道估计的影响.仿真结果显示,本文的方法能达到很好的信道估计性能,同时能够降低OFDM的峰均比.     

一种基于概念层次数据库挖掘一般化关联规则的算法研究

从数值型数据库中挖掘出关联规则是一个很有应用前景的课题.在实际中,通常属性内还存在更高层次的概念抽象,即呈现出层次结构.本文基于这一结构,首先将原来的数据库扩展成层次数据库,然后提出了从此数据库中,挖掘出更一般关联规则的方法.运行实例表明了本文提出方法的有效性.     

用有限元法确定弹塑性材料结构的极限承载力

确定弹塑性材料结构的极限承载能力是结构设计中极其重要的一个问题,它通常是采用弹塑性非线性有限元方法来进行分析的.本文提出了利用基于一系列线弹性有限元解来获得弹塑性材料结构的极限承载能力的试验误差法,并将它与切线法和割线法进行了比较和讨论.在计算的每一步中,根据应力松弛系数降低杨氏弹性模量,并将结构的应力松弛系数和作为误差指标.当结构的误差指标小于给定的误差容限时就得到收敛解.本文方法可计算出结构受载后直到崩溃时应力、应变和载荷-变形曲线.数值实验表明,本文方法是有效的和可行的.     

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。