COSPAS／SARSAT搜救卫星系统的开发与应用

ＣＯＳＰＡＳ／ＳＡＲＳＡＴ搜救卫星系统是由低极轨道卫星、地面用户终端，任务控制中心和应急示位标组成，主要用于确定在１２１．５ＭＨｚ频率上发射的遇险示位标位置，从而准确地测定遇险者的方位，提供迅速有效地营救。     

406MHz紧急无线电示位标在海上的应用

此文在介绍ＣＯＳＰＡＳ－ＳＡＲＳＡＴ搜救卫星系统基础上，介绍了４０６ＭＨｚ ＥＰＩＲＢ的特点、操作要求和使用注意事项。     

国际海事卫星组织的通信业务

国际海事卫星组织的主要任务和目的是利用ＩＮＭＡＲＳＡＴ卫星，陆上地球站和各种ＩＮＭＡＲＳＡＴ移动站，为全球提供海事通信服务。     

自主式水下潜器海洋环境监测系统技术概念

介绍了被誉为未来海洋卫星的自主式水下潜器ＡＵＶ（Ａｕｔｏｎｏｍｏｕｓ Ｕｎｄｅｒｗａｔｅｒ Ｖｅｈｉｃｌｅｓ）的国外发展新动态、自主式海洋采样网络ＡＯＳＮ（Ａｕｔｏｎｏｍｏｕｓ Ｏｃｅａｎ Ｓａｍｐｌｉｎｇ Ｎｅｔｗｏｒｋ）和海洋中的“卫星”技术概念和应用前景。     

INMARSAT第三代卫星及其点波束技术

介绍了ＩＮＭＡＲＳＡＴ新一代的卫星即ＩＮＭＡＲＳＡＴ第三代卫星及其所采用的新技术－－－点波束技术。     

INMARSAT—M船站的安装与启用

此文阐述了，国际移动卫星组织新近投入营运的ＩＮＭＡＲＳＡＴ－Ｍ标准系统的船舶地球站的安装和启用试验程序及安装注意事项。     

一种新型的船用计程仪

本文介绍了ЛДＢ－１型多普计程仪，其特点是精度高，使用方便，工作可靠，有航速和航程输出接口，信号可直接送ＡＲＰＡ雷达和卫星导仪以及综合导航系统。     

利用卫星遥感分析闽江口深水航道演变

通过对7个时相Landsat卫星TM影像资料处理与信息提取,研究闽江口在不同时相、不同径流和不同时刻的悬浮泥沙来源、分布、扩散和潮汐动力。据此,分析影响闽江口深水航道演变因素,整治航道提供依据。     

变形率对CuAlBe合金与不锈钢扩散焊接头强度的影响

针对ＣｕＡｌＢｅ合金与不锈钢扩散连接,研究了扩散焊工艺参数对接头变形率的影响以及接头的变形率与接头强度的强度。研究结果表明,随温度,压力和时间增加,ＣｕＡｌＢｅ合金变形率迅速增加,而１Ｃｒ１８Ｎｉ９Ｔｉ变形率较小;随变形率增加,界面紧密接触,接头强度增加,当变形率较小时界面有未焊合存在。液相扩散焊时,随变形率增加,接头强度增加。     

交通部专用卫星通信网简介及应用

介绍了交通部专用卫星通信网的整体概况，支持的业务种类以及网中ＴＤＭＡ卫星终端站的组成结构，同时对专网的开通为天津港的业务经营带来的诸多优势，作了详细的图文分析。     

从河床特性与演变角度评长江中下游张家洲浅水航道的开发与整治

长江中下游张家洲河段属分汊河床，由“张家洲”江心洲将河床分为南港与北港。在枯水期南港与北港的诸浅滩水深不足３．８ｍ，严重影响航运。本文根据地理调查，近１００年来历史航道图的比较，航道水深的测量值，以及河床水力几何形态关系的分析，着重研究了张家洲浅水航道的河床演变与南北两港及其浅滩的河床水力几何形态，探讨的成果可作为张家洲浅水航道的整治以及长江中下游航道的开发规划与建设的参考。     

人字门启闭力影响分析及Z值选取

目前设计规范未对人字门启闭力计算公式中的闸门前后水压差Z值选取做出明确规定,在计算人字门启闭力时通常会取大值,从而导致工程浪费。对大藤峡船闸人字门水动力与启闭特性进行数值模拟和物理模型试验研究,定量分析启闭力影响因素的效果,以便更科学合理地选取Z值。结果表明,适当增大门底间隙、门龛深度和采用变速启闭运行方式有利于闸门前后水体流动顺畅,在闸门启闭过程中形成的Z值则较小,相应的人字门启闭力也变小。综合考虑人字门启闭运行水动力特性的影响因素,合理选取Z值,可得到比较准确的计算结果,优化启闭机容量。     

钢壳混凝土沉管组合结构徐变和收缩性能研究

以深圳到中山预投标的钢壳混凝土沉管隧道工程为例,针对钢壳混凝土沉管的组成形式,借鉴已有的钢-混凝土组合结构在收缩和徐变作用下的变形研究成果,对钢壳混凝土结构在长期作用下的受力和变形情况进行研究,采用一种简捷的计算方法对沉管横向结构在长期作用下的受力和变形情况进行计算.结果表明:由于徐变和收缩的影响,混凝土最终将近退去一半的应力值;钢壳的受力随着徐变和收缩的发展趋于均匀;随着收缩徐变的发生钢壳所承担的弯矩逐渐减小;由于徐变和收缩导致挠度增量的影响并不大.     

基于强度折减法的镇压层对海堤稳定性的影响

镇压层对软土地基上海堤稳定性提升具有重要作用,但其宽度、厚度的选择大多凭经验公式以及极限平衡法进行选择和计算。基于强度折减法,利用ABAQUS有限元软件对镇压层的宽度、厚度与海堤安全系数之间关系进行研究。首先介绍强度折减法的基本原理,之后建立相关海堤模型。将镇压层宽度及厚度以线荷载宽度及大小的形式添加到模型中,以数值计算收敛与否作为评价标准计算得到安全系数以及潜在滑动面。从滑动面角度分析安全系数与镇压层宽度变化的原因。结果表明:海堤稳定性与镇压层宽厚及厚度成正比关系,且宽度超过一定值后,安全系数以及滑动面均不再发生改变。     

OCS development: A new law and a new beginning

Abstract

This article reviews the conflicts that led to the establishment of a special Congressional Committee on offshore oil and gas exploration, development, and production and the attempted resolution of various issues by that Committee and the Congress in the 1978 Amendments to the Outer Continental Shelf Lands Act of 1953. A short review is provided of the history of Outer Continental Shelf (OCS) development, of the conflict between the federal government and other interested entities and persons, and of the Congressional mechanism to respond to these conflicts. A more detailed analysis is provided of the most significant OCS issues. The article describes the various risks and benefits of offshore activity and the various benefits and risks of proposed changes in the law concerning such development. A review of the Congressional mechanism to assess these risks and benefits and balance them is included in a discussion of the various issues and legislated solutions. Finally, the article notes the need for continuing oversight and review of the benefits and risks and how effective the 1978 Amendments are in balancing them.     

Piracy, navies and the law of the Sea: the case of Somalia

This contribution concentrates on the legal aspects of piracy and tries to explain some of the practical problems which modern navies experience in their fight against piracy and maritime violence off Somalia. The UN Law of the Sea Convention of 1982 provides a traditional though largely deficient set of rules for control and counter measures. Modern legal instruments such as the SUA Convention of 1988 as amended, recent resolutions of the UN Security Council and regional treaties try to fill the loopholes. Against this background the paper discusses e. g. the law of boarding and investigation of suspicious vessels, the arrest and penal prosecution of criminals and the right of self-defence in case of an imminent attack. The international mandates and the national rules of engagement in which the navies operate reflect these ambiguities that result in a loss of momentum. After all piracy is not an act of war, but a crime. In conclusion apolitical solution on land is indispensable as the navies and coast guards can only fight the symptoms and not the causes of crime and unrest in a failed State.     

预压软土地基对超长群桩承载性状的影响

建立超长桩和土体共同作用的三维非线性有限元数值模型,采用预压排水固结法研究软土地基预压后超长桩的承载特性,分析地基土固结沉降、桩身侧摩阻力、桩顶位移-荷载曲线和桩身轴力的变化规律。通过运用控制变量法对预压时间和预压荷载以及不同土质的预压效果进行分析,对比分析单桩与群桩对预压效果的敏感度,并分析固结度对超长桩承载性状的影响。结果表明:预压能较好地改善地基、提高超长群桩的承载能力。增大预压荷载,可增大土体的固结沉降和桩身侧摩阻力;延长预压时间,可提高桩身侧摩阻力,减小桩顶沉降和桩身轴力;预压对群桩的影响好于单桩;固结度越大,超长群桩承载性能越好;对于粉质黏土、黏土以及淤泥质粉质黏土,当预压时间分别达到90 d及180 d时,地基固结基本完成,预压不再改变土的力学指标。     

Development of and prospects for cruising in Europe

This paper evaluates the development of prospects for cruising in Europe. It examines this within the broad framework of economic theory and maritime economics. Initially, the market structures and relationships applicable to cruising are considered with particular attention being paid to the linkages between the shipping markets and tourism and leisure. This conceptual analysis suggests that whilst cruising has a strong shipping element it does not fall exclusively within the classic framework of maritime economics but draws from both shipping and tourism and leisure. For reasons of clarity, a number of definitions are also provided covering maritime tourism and leisure, cruising, and supply and demand, as it relates to cruising. Following this, an overview of the cruise industry is included. This focuses primarily on the growth in the demand both world wide and at regional level. In particular, the analysis places the development of cruising in Europe in market perspective. Subsequently, the development of cruising in the UK is examined as a case study. Initially, UK market growth is analysed and it can be seen that the UK is now the second largest cruise market in the world after North America. Projections of the growth in UK demand to 2003 are also provided. The growth in supply is also studied and the UK targeted fleet is identified. In addition, the question of ownership is addressed. The prospects of employment for UK seafarers within the cruise industry are also considered and results obtained from the analysis suggest that it should be possible to increase the participation of UK and other European seafarers within the cruise industry at all levels and in all departments. In the final section of the paper, the position of UK ports as terminals and destinations is evaluated. It is concluded that the fundamentals of the cruise business remain strong, and continued growth by the industry should be possible for the foreseeable future.     

Trophic flows,ecosystem structure and fishing impacts in the South Catalan Sea,Northwestern Mediterranean

An exploited ecosystem from the continental shelf and upper slope of the Northwestern Mediterranean Sea was described by means of an Ecopath mass-balance model with the aim of characterising its functioning and structure and describing the ecosystem impacts of fishing. This application included some complexities added to the general modelling methodology due to the high biodiversity of the Mediterranean Sea and the multispecific nature of the fishery, and to the difficulties of working with fishing data which are usually irregularly or imprecisely collected. The model comprised 40 functional groups including primary producers, the main species of benthic, demersal and pelagic invertebrates, fishes and non-fish vertebrates and three detritus groups. In addition, trawling, purse seine, longline and troll bait fishing fleets were included.Results showed that the functional groups were organized into four trophic levels with the highest levels corresponding to anglerfish, dolphins, large pelagic fishes and adult hake. The system was dominated by the pelagic fraction, where sardine and anchovy prevailed in terms of fish biomasses and catches. Detritus and detritivorous groups also played key roles in the ecosystem and important coupled pelagic-demersal interactions were described. Considering Odum's theory of ecosystem development, the ecosystem was placed on an intermediate-low developmental stage due, at least partially, to the impact of fishing activity. This highlighted the high intensity of fishing in the ecosystem, in accordance with the general assessment of western Mediterranean marine resources, and fishing fleets were ranked as top predators of the system. The low trophic level of the catch was in line with the long history of exploitation in the area. However, the steady decline of pelagic landings between 1994 and 2003, coupled with a decrease of the pelagic biomass within the system, underlined the low resistance of the system in front of perturbations. This decline was reproduced under Ecosim dynamic simulations combining different scenarios of moderate increase of fishing effort and an environmental forcing affecting the availability of preys to small and medium-sized pelagic fishes under wasp-waist flow control.     

软基上大型砂袋围堤中袋体的作用

大型砂袋围堤作为软土地基上围堤修建的新技术,提高了围堤的凝聚力和整体性,能较好地适应软土地基的变形。受袋体作用的影响,大型砂袋围堤的整体力学和工程特性发生了较大的改变。合理确定砂袋的力学、工程特性,判断其对围堤整体稳定性的影响是模拟砂袋围堤、设计计算特征参数的依据。分析大型砂袋围堤中袋体作用的研究现状,总结模型试验、数值分析和理论推导3方面的研究成果和进展,对工程应用和未来研究的发展方向提出了针对性建议。