现代喷水推进装置的演变

现代喷水推进装置已有340多年的历史,其演变过程主要经历了早期的喷射推进、液压泵推进、间歇性喷水推进、底板式喷水推进、尾板式喷水推进和外挂式喷水推进等几种类型,文中对各种类型喷水推进装置作了简要介绍;列举了喷水推进在现代各国舰船上的应用;最后归纳了喷水推进装置应用的特点,并就其未来的发展作了展望。     

明渠水力设计中的能耗极值假说

最小能耗率理论和最大能耗率理论是水力学及河流动力学研究中容易混淆的两种假说。文章从明渠的最优水力断面设计、临界渠道设计、冲积河流河相关系3个方面出发,在理论上证明了能耗极值假说的存在,说明能耗极值假说取最小值和最大值与约束条件、已知条件之间的关系,并将计算结果与现有成果进行了比较。     

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。     

浅析小流量山区河流航道尺度的论证方法

航道整治尺度的确定是航道整治工程可行性论证的重要内容之一,针对山区小流量河流,提出了水力计算法、滩情分析法、类比法,来确定合理的航道尺度。并以赤水河航道整治工程为实例进行了计算和综合分析,工程实践表明提出的计算方法是有效的。     

Spatial and Temporal Changes in Access Rights to Shellfish Resources in British Columbia

Over the past decade, the shellfish and finfish aquaculture industry has expanded rapidly in coastal British Columbia (BC) Canada. Foreshore and nearshore shellfish and finfish aquaculture leaseholds are sited in close proximity or in direct competition with habitat for wild shellfish. As a result, some wild shellfish harvesters believe shellfish farms are significantly reducing access to beaches and estuarine areas for wild harvesting, or that salmon farms are contaminating wild shellfish stocks. In this article, Geographic Information Systems (GIS) are used to analyze spatial and temporal trends in the growth of shellfish and finfish aquaculture tenures in BC, while interviews with stakeholders in coastal communities are used to explore user conflicts and the implications of changing access rights on the distribution of marine resources. Qualitative and quantitative findings suggest that shellfish aquaculture provides significant economic opportunities for coastal communities, but that such development may hold increased risk of spatial conflicts over marine habitat as the aquaculture industry continues to grow.     

扭王字块随机安放细则

某海外深水防波堤工程中选用了国内的扭王字块作为护面结构,但国标中有关扭王块安装规则的内容较少,因此在与外方咨工交涉过程中遇到一些安装细则的困扰,如扭王字块的最佳坡比,块体的详细姿态要求,堤身、堤头、堤顶等位置的具体安装顺序等问题。参照国外同类块体的技术,总结了数十年来我国工程技术人员在设计、物模试验、施工中积累的安放经验,整理出扭王字块安装中一些有益的安装细则,可为类似工程提供参考。综合而言,定点随机安装是最能充分发挥扭王字块优异水动力性能的安放方法。安装点位预定义图、水下可视化安装等新技术的应用能大幅提高扭王字块的安装质量。     

长江口深水航道分流比与汊道稳定性评估

潮汐河口汊道整治工程通常引起工程所在一支汊道分流比减少,目前对这种分流比减少的河势效应缺乏量化的评估.通过窦国仁河相方程,探讨长江口深水航道整治工程开工以来北槽水、沙条件的变化与河相调整间的相关关系.结果显示:1)整治工程可产生的河相调整幅度小于实际增幅.期间,大规模的疏浚工程和区域含沙量的降低是平衡河相实际调整的两大...     

Remote Sensing for Coastal Area Management in China

Satellite remote sensing technique has been used to observe the coastal area. This article reviews applications of remote sensing to coastal area management (CAM) in China. These applications include the coastal resource and island mapping, coastal environmental change and coastal hazard monitoring, oceanographic parameter measurement, and coastal process restudy. Future applications are also discussed.     

VLCC液压阀门遥控系统布置的设计与优化

为降低VLCC阀门遥控系统的建造成本和液压油泄漏的风险,提高施工质量及使用维护的便捷性,以某30万t VLCC的建造实例为基础,在对该项目液压阀门遥控系统的设计和施工情况进行详细调查分析的基础上,统计现场部分区域的液压油单芯管、卡套穿舱件等附件的物量,提出针对电磁阀箱和液压泵站舱室布置的设计优化方案。在进行修改后发现,可减少总长约1 827.84m的液压油单芯管、204个卡套穿舱件等相关附件的用量,为企业提高建造质量、实现降本增效提供可行性方案。     

Advancing Coastal Habitat Resiliency Through Landscape-Scale Assessment

Coastal areas are among the most biologically rich regions in the world. They provide tremendous benefit to people through ecological services like pollution filtration, carbon sequestration, and storm protection. However, human activity has decreased the ability of ecosystems to provide these services, and in many coastal areas, restoration is not as effective as it could be. Limited success is largely attributed to vague goals and a lack of holistic, science-informed planning. Quantifying coastal habitat health can aid in setting better restoration goals and lead to greater restoration success. The Long Island Sound Study National Estuary Program conducted the first comprehensive look at coastal habitat health for the Long Island Sound Estuary. In this study we also reviewed landscape-scale habitat assessment progress within other coastal programs. Results can be applied to establish ecosystem health-oriented goals that improve habitat function and resilience across coastal areas.     

阀门液压遥控系统在海洋工程中的设计研究

摘要：阐述了阀门液压遥控系统的泵站组成基本原理。讨论了海洋工程中常用的阀门遥控系统的几种基本形式及选用原则、应急系统的操作应用和设计选用对策,研究提出了设计选型的关键原则以及安装、投油的重要性及注意事项和调试的方法等。     

西江(桂梧段)优良河段及其河相关系分析研究

从航道工程的角度,概括总结优良河段及河相关系的研究和应用现状,提出了在冲淤资料缺乏时,优良河段的选择方法,并实际应用于西江桂梧河段,选取18个优良河段进行沿程横断面河相关系统计分析,成功建立了低水期零水位下的河相关系式,为航道整治规划提供参考。     

Open boundary conditions in stratified ocean models

In most applications of numerical ocean models, artificial boundaries are introduced to limit the domain. Along such a boundary we need to apply what is often referred to as an open boundary condition (OBC). In this paper a number of local methods used in barotropic ocean models are applied and discussed for the stratified case using a normal mode approach. The OBCs are the simple conditions: clamped, prescribed and zero gradient; the radiation conditions: Camerlengo–O'Brien, Orlanski and a method of characteristics based on linear equations; and a sponge type condition: the flow relaxation scheme. The OBCs have been implemented in a 3-layer ocean model and examples of how the various OBCs perform for three simple flow situations are investigated. The cases are: internal wave radiation, a quasi-steady coastal jet and the response to a storm moving across a strait. It is found that the flow relaxation scheme and the method based on characteristics perform well for the test cases in general, although some of the simpler methods give better results in individual cases.     

明渠交汇口水流浅水二维数学模型研究

针对明渠交汇口缓流流动特性,建立基于高性能有限体积数值方法、具有二阶精度的非恒定浅水二维水流数学模型。基本控制方程采用浅水二维水流方程;采用能够有效捕捉激波的高性能有限体积方法离散控制方程;采用了隐式方法处理阻力项,从而保证了模型的稳定性。采用非结构三角形网格系离散计算区域。最后,应用实测资料对两种模型进行了验证比较,结果表明该模型可模拟明渠交汇口基本流动特性,显示了对天然河流广阔的应用前景。     

A numerical study of stochastic larval settlement in the California Current system

Key to the predictive understanding of many nearshore marine ecosystems is the transport of larvae by ocean circulation processes. Many species release thousands to billions of larvae to develop in pelagic waters, but only a few lucky ones successfully settle to suitable habitat and recruit to adult life stages. Methodologies for predicting the larval dispersal are still primitive, and simple diffusive analyses are still used for many important applications. In this study, we investigate mechanisms of larval dispersal using idealized simulations of time-evolving coastal circulations in the California Current system with Lagrangian particles as models for planktonic larvae. Connectivity matrices, which describe the source-to-destination relationships for larval dispersal for a given larval development time course, are used to diagnose the time–space dynamics of larval settlement. The resulting connectivity matrices are shown to be a function of several important time scales, such as the planktonic larval duration, the frequency and duration of larval release events and inherent time scales for the coastal circulations. Many important fishery management applications require knowledge of fish stocks on a year-to-year or generation-to-generation basis. For these short time scales (typically less than 1 year), larval dispersal is generally far from a simple diffusive process and the consideration of the stochastic and episodic nature of larval dispersal is required. This work provides new insights into the spatial–temporal dynamics of nearshore fish stocks.     

The potential for British coastal shipping in a multimodal chain

A strategy to revitalize coastal shipping within Great Britain is investigated. An examination of the regulatory environment shows government, at both the EU and British levels, aware of the environmental benefits of coastal shipping compared to road freight transport, if only mildly supportive in tangible terms. The geography of Great Britain and the modern preference for just-in-time deliveries have severely restricted the ability of coastal shipping to compete effectively with road freight transport. The primary objective of the paper is to investigate whether coastal shipping could be integrated into a multimodal door-to-door supply chain, where it is currently hampered by high costs of transhipment, slow transport speeds, and the incongruity of load sizes between land and sea modes. Integration requires the co-operation of all organizations within the multi-modal supply chain. However, coastal shipping companies have been known to be individualistic and mistrusting of alliances. Therefore, a Delphi study is undertaken to investigate the standpoint of leading managers in such companies towards multimodal integration. The results of the Delphi study indicate that managers are in favour of multimodal developments, in particular cooperation between coastal shipping and road haulage. However, there was agreement that the business is highly competitive, and this may prevent the forms of collaboration required for multimodal systems. The secretive nature of the coastal shipping sector could impede joint marketing to promote a mode of transport that is often 'invisible' to shippers. There was little consensus on the relationship that should exist between coastal shipping and ports, a topic worthy of further investigation.     

The potential for British coastal shipping in a multimodal chain

A strategy to revitalize coastal shipping within Great Britain is investigated. An examination of the regulatory environment shows government, at both the EU and British levels, aware of the environmental benefits of coastal shipping compared to road freight transport, if only mildly supportive in tangible terms. The geography of Great Britain and the modern preference for just-in-time deliveries have severely restricted the ability of coastal shipping to compete effectively with road freight transport. The primary objective of the paper is to investigate whether coastal shipping could be integrated into a multimodal door-to-door supply chain, where it is currently hampered by high costs of transhipment, slow transport speeds, and the incongruity of load sizes between land and sea modes. Integration requires the co-operation of all organizations within the multi-modal supply chain. However, coastal shipping companies have been known to be individualistic and mistrusting of alliances. Therefore, a Delphi study is undertaken to investigate the standpoint of leading managers in such companies towards multimodal integration. The results of the Delphi study indicate that managers are in favour of multimodal developments, in particular cooperation between coastal shipping and road haulage. However, there was agreement that the business is highly competitive, and this may prevent the forms of collaboration required for multimodal systems. The secretive nature of the coastal shipping sector could impede joint marketing to promote a mode of transport that is often ‘invisible’ to shippers. There was little consensus on the relationship that should exist between coastal shipping and ports, a topic worthy of further investigation.     

基于SVM的液压设备仿真模型的故障诊断

阐述了SVM算法在液压系统的故障诊断领域中的应用及其诊断效果.以全液压克令吊模型为研究对象,将克令吊模型的回转回路作为一个独立系统,使用功率键合图方法建立其数学模型,并用Matlab中的Simulink对模型进行计算机仿真,对回转回路选择不同的参数进行流量的特性仿真,运用支持向量机理论依据流量值的特性对回转回路进行故障分类,得到了令人满意的故障分类正确率.     

铺缆船用电缆埋设犁土壤挖掘阻力计算

传统的计算埋设犁土壤挖掘阻力的方法一般采用经验公式计算。经验公式依赖丰富的试验数据，且只能适应特定形状和尺寸的埋设犁。由于埋设犁的形状和尺寸各不相同，基于经验公式计算土壤挖掘阻力的方法准确性不高。根据土力学基本原理，在力学分析的基础上，运用数学方法进行公式推导，得到用于计算不同形状尺寸埋设犁挖掘阻力的理论方法，解决依赖经验公式计算土壤挖掘阻力的局限性。     

跨大面积水域的水准测量在地基处理工程监测中的应用

水准测量的精度和效率直接关系到港口及海岸工程的进度、质量和成本,由于跨大面积水域的测量路线较长,如果观测时前、后视线不相等就会产生较大的测量误差,采用跨河水准测量的方法可以较好地解决这一问题。结合某吹填区地基处理工程监测工作的实践,重点介绍跨大面积水域进行水准测量的方法和步骤,可供类似工程参考。