P-201遇水膨胀止水胶在厦门海底隧道中的应用

施工防排水是海底隧道施工成败的核心技术之一,厦门海底隧道设计防水等级为地下工程Ⅰ级防水,要求无渗漏和结构表面无湿渍.文章主要介绍了P-201遇水膨胀止水胶在厦门海底隧道中的应用及其物理性能指标、施工工艺、技术要求等,对同类地下工程防水施工具有一定的借鉴意义.     

Receiver autonomous integrity monitoring availability and fault detection capability comparison between BeiDou and GPS

This paper used the statistical methods of quality control to assess receiver autonomous integrity monitoring （RAIM） availability and fault detection （FD） capability of BeiDou14 （Phase II with 14 satellites）, BeiDou （Phase III with 35 satellites） and GPS （with 31 satellites） for the first time. The three constellations are simulated and their RAIM performances are quantified by the global, Asia-Pacific region and temporal variations respectively. RAIM availability must be determined before RAIM detection. It is proposed that RAIM availability performances from satellites and constellation geometry configuration are evaluated by the number of visible satellites （NVS, NVS 〉 5） and geometric dilution of precision （GDOP, GDOP 〈 6） together. The minimal detectable bias （MDB） and minimal detectable effect （MDE） are considered as a measure of the minimum FD capability of RAIM in the measurement level and navigation position level respectively. The analyses of simulation results testify that the average global RAIM performances for BeiDou are better than that for GPS except global RAIM holes proportion. Moreover, the Asia-Pacific RAIM performances for BeiDou are much better than that for GPS in all indexes. RAIM availability from constellation geometry configuration and RAIM minimum FD capability for BeiDou14 are better than that for GPS in Asia-Pacific region in all cases, but the BeiDou14 RAIM availability from satellites are worse than GPS＇s. The methods and conclusions can be used for RAIM prediction and real-time assessment of all kinds of Global Navigation Satellite Systems （GNSS） constellation.     

Incentives to reduce port inefficiency: a theoretical approach

Over the last decades, the European Union (EU) has devoted a large amount of effort and money to projects aimed at boosting some of its maritime corridors as a modal alternative to road or rail freight transport. However, the overall design of most of these programmes has ex post revealed as very ineffective. This paper suggests that promoting port efficiency might be a more suitable target to increase the modal split of Short Sea Shipping (SSS) than subsidizing firms to transfer cargo from road to sea. But defining ‘port efficiency’ is a complex task and, therefore, granting money directly to port authorities could also generate perverse moral hazard effects, particularly when the improvements are difficult to monitor and many investments are non-refundable. The European Court of Auditors points out that millions of EU public port finance was wasted on empty terminal and other unused infrastructure. The objective of this paper is to design a proper subsidy to promote SSS by encouraging port improvements through a proper system of incentives. As a policy recommendation, in this paper we propose the development of a subsidy per inefficiency-reduction unit.     

基于能效管理的船舶航速系统优化设计

在目前航运业市场低迷、运力过剩的境况下,航运企业愈发重视对燃油成本的控制,对航速节油也有了更多的要求.为此,提出基于能效管理的船舶航速系统优化设计,计算船舶营运的经济航速.并结合航次的航线、航向、航速及每段航线的天气、水文等信息,对船舶营运航速的模型进行不断优化调整,指导船舶航行,为船舶及船岸操作提供决策支持,以达到优化节能的目的.     

有限元分析在客车轻量化设计中的应用

采用HYPERMESH软件建立某大型公路客车的有限元模型,对整车结构使用OPTISTRUCT软件进行有限元分析。依据分析结果,在保证整车结构运行刚度和强度的情况下,对整车结构进行轻量化设计。最后对轻量化结构进行侧翻分析和优化设计,以保证整车上部结构强度的侧翻安全性。     

基于时间硬化模型的路面车辙预估分析

为了对路面结构车辙发展进行定量的预估分析,本文建立了三维路面有限元模型,基于时间硬化的蠕变本构模型对三种典型结构的车辙进行了预估分析。结果表明,基于该模型的预估方法能够有效的模拟车辙发展。     

浅析船舶舾装部件标准库的软件实现方法

本文首先指出了目前在船舶设计中涉及到部件标准化的一些问题,然后通过建立业务环境来明确部件标准化在船舶设计中的作用.另外从软件开发的角度描述了船舶舾装专业部件标准库的树形结构.对于标准库中的每一个条目,确定了建立每个标准工艺属性与图形信息的方法.     

Disruption risks and mitigation strategies: an analysis of Asian ports

The critical nature of a seaport is a connection point. In addition to the effect on port operations, a port disruption will be a strain on trade flows and the various parties concerned. Climate change, oil spill, security, social and political instability are increasing concerns over the years which would lead to higher risks. With significant growing trade volume in Asia, there is a pressing need for comprehensive studies to prepare ports for disruptions. This paper aims to analyse and categorise the disruptions that have occurred in Asian ports and estimate the likelihood of recurrence based on the data since the year 1900. Results reveal a rising trend of disruptive events. Natural disasters and labour strikes are the two main causes of port disruptions, while natural disasters lead to the highest severity in terms of cargo tons affected. Mitigation strategies proposed in terms of both preventive and reactive measures are specifically designed to reduce the likelihood and severity of the various types of port disruptions. The paper provides recommendations on risk mitigation for relevant parties.     

Traffic Performance Models for Dynamic Traffic Assignment: An Assessment of Existing Models

Abstract

This paper provides a review of the traffic performance models for dynamic traffic assignment (DTA) and it identifies the strength and weakness of existing models. Requirements for traffic performance models are identified and various forms of existing traffic performance models for DTA are reviewed and analysed according to the requirements. Non‐linear travel time models are shown to have some deficiencies that make them unsuitable for the analysis of time‐varying transportation networks. Even though linear‐type travel time models are identified as good candidates for the analysis of dynamic transportation networks, they have limitations from the practical point of view that travel time increases only linearly with the amount of traffic on the link. This poses a dilemma and it seems to be one whose resolution is an imminent precondition for DTA modelling to progress in a way that is both theoretically coherent and plausible in practical terms.     

Robust adaptive horizontal vibration isolation of towed seismic streamers

The horizontal vibration of towed seismic streamers is a main reason for efficiency reduction of the seismic survey and tail tangling. A vibration suppression scheme of towed seismic streamers is investigated in this paper. The towed seismic streamer is divided into two spans, a controlled span, i.e., the low tension span, and an uncontrolled span, i.e., the high tension span, by a bird. The system model includes a hyperbolic partial differential equation with variable coefficient describing the towed seismic streamers, and an ordinary differential equation describing the dynamic of bird. Robust based-model knowledge and adaptive controllers, based on the Lyapunov method, are designed to isolate the vibration of towed seismic streamers caused by the course deviations of towing vessel, the variations of towing vessel velocity and the variations of towed seismic streamer density. The robust based-model knowledge and adaptive controllers exponentially and asymptotically drive the span-towed seismic streamer displacement to zero, respectively. A finite difference scheme is used to validate the efficiency of the control law. The proposed controller can isolate effectively the disturbance originated from the towed vessel, and can provide the improved damping but not sacrifice the isolation performance. The adaptive scheme can tolerate the lack of knowledge of some uncertain parameters and can directly execute the online adjustment of the parameters. Meanwhile, the proposed control law is robust and can resist the model uncertainty due to parameter incertitude, model error and unknown disturbance and so on. The control law only includes velocity and slope, while it does not need the displacement which is difficult to measure in the practical operations. Thus it is easy to implement.