迎接STCW‘95公约的挑战

介绍了英国喀里多尼亚ＭａｃＢｒａｙｎｅ公司驾驶员与轮机员的培训模式,并对其进行了分析。     

Using BDI agents to improve driver modelling in a commuter scenario

The use of multi-agent systems to model and to simulate real systems consisting of intelligent entities capable of autonomously co-operating with each other has emerged as an important field of research. This has been applied to a variety of areas, such as social sciences, engineering, and mathematical and physical theories. In this work, we address the complex task of modelling drivers’ behaviour through the use of agent-based techniques. Contemporary traffic systems have experienced considerable changes in the last few years, and the rapid growth of urban areas has challenged scientific and technical communities. Influencing drivers’ behaviour appears as an alternative to traditional approaches to cope with the potential problem of traffic congestion, such as the physical modification of road infrastructures and the improvement of control systems. It arises as one of the underlying ideas of intelligent transportation systems. In order to offer a good means to evaluate the impact that exogenous information may exert on drivers’ decision making, we propose an extension to an existing microscopic simulation model called Dynamic Route Assignment Combining User Learning and microsimulAtion (DRACULA). In this extension, the traffic domain is viewed as a multi-agent world and drivers are endowed with mental attitudes, which allow rational decisions about route choice and departure time. This work is divided into two main parts. The first part describes the original DRACULA framework and the extension proposed to support our agent-based traffic model. The second part is concerned with the reasoning mechanism of drivers modelled by means of a Beliefs, Desires, and Intentions (BDI) architecture. In this part, we use AgentSpeak(L) to specify commuter scenarios and special emphasis is given to departure time and route choices. This paper contributes in that respect by showing a practical way of representing and assessing drivers’ behaviour and the adequacy of using AgentSpeak(L) as a modelling language, as it provides clear and elegant specifications of BDI agents.     

Analysis of equilibrium automobile holdings in Israel with aggregate discrete choice models

Models of household vehicle ownership decisions do not suffice as a basis for forecasting the size and composition of aggregate vehicle holdings. Forecasting applications require that such models be imbedded in systems describing the operation of the automobile market. This paper presents a new model of short run equilibrium in the automobile market. The short run is a period within which new car designs and prices are fixed but used car prices adjust competitively to market forces. The magnitude and mix of new car sales, the extent of used car scrappage and the composition of used car holdings are determined in equilibrium with used car prices. An econometric version of the market model has been estimated on Israeli data and applied to analyze the impact of vehicle tax policy on automobile holdings in Israel. The paper describes this application.     

Dissolved organic matter in shelf waters off the Ría de Vigo (NW Iberian upwelling system)

Net in situ production and export of dissolved organic carbon (DOC) and nitrogen (DON) have been studied in shelf waters off the Ría de Vigo (NW Spain), as part of a comprehensive hydrographic survey carried out from September 1994 to September 1995 with a fortnight periodicity. DOC and DON correlated well (r=+0.78), the slope of the regression line being 12.0±0.7 mol-C mol-N⁻¹, about twice the Redfieldian slope of particulate organic matter, 6.5±0.2 mol-C mol-N⁻¹ (r=+0.95). Labile DOC and DON accumulated in the upper 50 m during the upwelling season (March–September), mainly after prolonged periods of wind relaxation, when horizontal flows were reduced. This labile material represented 50% and 35% of the total (dissolved+particulate) organic carbon and nitrogen susceptible of microbial utilisation, which assert the key contribution of dissolved organic matter (DOM) to the export of new primary production in the NW Iberian upwelling system. This surface excess in shelf waters appeared to be formed into the highly productive Ría de Vigo (a large coastal indentation) at net rates of 4.4 μM-C d⁻¹ and 1.3 μM-C d⁻¹ in the inner and outer segments of the embayment respectively, and subsequently exported to the shelf. Once in the shelf, simple dilution with the inert DOM pool of recently upwelled Eastern North Atlantic Central Water (ENACW) occurred. Eventually, the DOM excess produced during the upwelling season is exported to the adjacent open ocean waters by the coastal circulation. Conversely, during the unproductive downwelling season (October–February), the lowest DOC and DON levels were recorded and export was prevented by the characteristic downwelling front associated to the seasonal poleward slope current.     

深厚砂卵石地层超深竖井施工降水模型试验研究北大核心CSCD

富水砂卵石地层中基坑降水始终是工程界较大的难题,文章针对兰州强透水深厚砂卵石地层超深竖井降水进行了理论计算和模型试验研究,研制了一套有效的模型试验系统,配置了砂卵石土体相似材料,并重点研究了基底注浆加固对基坑降水的影响。研究结果表明:(1)黄河对基坑降水有重要的影响,靠近黄河一侧降水漏斗曲线陡直,远离黄河一侧降水漏斗曲线平缓;(2)基底注浆降低了水力梯度,提高基坑施工安全性,可有效减少基坑内抽水量,但对于坑外抽水量作用不大;(3)基底加固区渗透系数存在最优值,对于该工程,建议取1×10^(-6)m/s为加固区目标渗透系数。     

CMC改性海水泥浆性质变化及砂地层成膜试验研究北大核心CSCD

为探究泥水盾构穿越海底砂地层时羧甲基纤维素钠(CMC)对海水泥浆性质及成膜效果的影响,配制不同CMC掺量的海水泥浆,分析泥浆泌水率、黏度、Zeta电位等性质的变化情况,并开展了泥浆渗透成膜试验。研究结果表明:相对于海水泥浆,加入CMC后的泥浆黏度逐渐增大,2h泌水率显著减小,形成的泥膜中结合水含量逐渐变大,泥膜渗透系数减小至4.03×10^(-8)cm/s;改性海水泥浆中粒径小于75μm的细颗粒含量显著增加,静置24h后,泥浆上部呈现浑浊,下部依然存在较严重的沉淀;当CMC掺量达到0.16%时,改性海水泥浆2h泌水率小于10%,成膜渗透流量小于0.01m^(3)/m^(2),可以保证泥浆短期稳定性并形成致密泥膜。     

Traffic congestion and economic context: changes of spatiotemporal patterns of traffic travel times during crisis and post-crisis periods

Transportation - This paper aims to evaluate the impacts of the economic context on traffic congestion and its consequential effects on private vehicle accessibility. We conduct a long-term...