Waiting profiles: An efficient protocol for enabling distributed planning of container barge rotations along terminals in the port of Rotterdam

We consider the problem of aligning barge rotations with quay schedules of terminals in the port of Rotterdam. Every time a barge visits the port, it has to make a rotation along, on average, eight terminals to load and unload containers. A central solution, e.g., a trusted party that coordinates the activities of all barges and terminals, is not feasible for several reasons. We propose a multi-agent based approach of the problem, since a multi-agent system can mirror to a large extent the way the business network is currently organized and can provide a solution that is acceptable to each of the parties involved. We examine the value of exchanging different levels of information and evaluate the performance by means of simulation. We compare the results with an off-line scheduling algorithm. The results indicate that, in spite of the limited information available, our distributed approach performs quite well when compared to the central approach. In addition, our experiments indicate that an information exchange based on waiting profiles reduces the average tardiness per barge with almost 80% when compared to the situation with no information exchange. We therefore think that waiting profiles provide a promising protocol to tackle this problem.     

A new roadway lighting measurement system

Past studies have shown that the level of roadway lighting is an important factor for nighttime roadway safety. To evaluate roadway lighting systems and maintain their functionality, it is essential to perform field lighting measurements. Currently, field measurements of roadway lighting systems are often conducted by handheld light meters using a short sample section. The evaluation of an entire corridor or a longer section is difficult when using the traditional manual measurement methods. This paper addresses this difficulty by developing a new lighting measurement system that can be used to collect massive amounts of lighting level data in an efficient, safe, and effective manner. The system consists of a light meter, a distance measurement instrument (DMI), a computer, software, and an electronic converter circuit to connect the computer and other hardware. Software was developed for the communication link between the computer and the light meter, and to record both the distance and illuminance data. The system was calibrated and validated with the field data. The new system will not only reduce future data collection costs, but also improve safety for field data collection personnel. The system has been approved for use to collect illuminance data on Florida state roads greater than or equal to 250-miles in length.     

电子地图零距离升级服务

经过2006年以来市场导入和培育,“导航”已经成为有车人士不再陌生的字眼,导航产品也拥有了数百万的用户群。随着用户逐步熟悉这个产品,“导航电子地图升级”成为越来越多用户关注的服务项目。     

单GPS定位导航产品将淡出江湖

随着城市和交通路网建设的发展,以及用户对产品认知的提高,用户开始对GPS导航产品的有效性产生了质疑,根源则是现今绝大部分市场上正在使用的导航产品完全依赖于GPS进行定位,由于技术特性的限制,该类导航产品存在很大的缺陷,这些缺陷导致了频繁的误入歧路或者无法给用户有效指导,甚至用户反映用不如不用的结论。     

Long-term development of express coach services in Britain

Express coach services compete for longer distance market with car and rail, and largely cater for the leisure, tourism, and visiting friends and relatives. markets. Britain deregulated its express coach system in 1980, and it is now opportune to examine long-term impacts of that change. The initial impacts were reviewed by the authors in 1986 (Robbins & White, 1986) but such impacts do not necessarily match long-term outcomes. Monitoring of the British system has been conducted by examining service changes and data on ridership, together with financial performance of the main operator groups and technical press coverage. It can be shown that a dominant position has been retained by the major operator (National Express), with a continued decline in the role of smaller independent operators in the all-year-round daily network. However, new competition has emerged from other large groups (most notably Stagecoach ‘Megabus’ in 2003). The paper analyses the operating and marketing strategies of the new operator and contrasts these strategies with those adopted in the 1980s. Implications for the future development of the network in Britain are outlined.     

NOBODY NEEDS A BOAT 作一名感觉销售者

生活对每个人来说都是必需的。作为一个行业,我们没有太多理由认为人们会受诱惑买我们的产品。的确,一个客户可能会对某船的尺寸和独特设计有兴趣,甚至对它的设计建造最细微的细节都感兴趣;但是从一开始就吸引他的其实是一个简单的感情,那就是这艘船给他的感觉如何。     

A two-dimensional response to a tropical storm on the Gulf of Mexico shelf

Surface current data from drifting buoys and remotely sensed wind data recorded over the continental shelf in the northeastern Gulf of Mexico during the passage of tropical storm Josephine in October 1996 are examined. Drifter data show the existence of a strong surface jet (velocities reaching 1 m s⁻¹) that moves up the west Florida shelf and westward along the Louisiana–Texas shelf, and lasts for nearly 1 week. The coastal jet occurs during an intense synoptic scale wind event where wind speeds reach 15 m s⁻¹. A simple force balance and statistical analysis are performed to assess the role of strong wind forcing. The primary balance shows an Ekman-type current. The role of local acceleration is greatest when winds are directed along bathymetry. A simple two-dimensional strongly forced shelf response model developed from the linear steady-state momentum equations also indicates larger along-shore currents due to both Ekman-type forcing by cross-shore winds and a cross-shore pressure gradient arising from conservation of mass. Model parameters fit empirically are within 15% of theoretical values. The simple model explains 30% and 46% of the variance in the observed along-shore and cross-shore surface currents, respectively.     

An inverse model for calculation of global volume transport from wind and hydrographic data

The P-vector inverse method has been successfully used to invert the absolute velocity from hydrographic data for the extra-equatorial hemispheres, but not for the equatorial region since it is based on the geostrophic balance. A smooth interpolation scheme across the equator is developed in this study to bring together the two already known solutions (P-vectors) for the extra-equatorial hemispheres. This model contains four major components: (a) the P-vector inverse model to obtain the solutions for the two extra-equatorial hemispheres, (b) the objective method to determine the Ψ-values at individual islands, (c) the Poisson equation-solver to obtain the Π-values over the equatorial region from the volume transport vorticity equation, and (d) the Poisson equation-solver to obtain the Ψ and depth-integrated velocity field (U, V) over the globe from the Poisson Ψ-equation. The Poisson equation-solver is similar to the box model developed by Wunsch. Thus, this method combines the strength from both box and P-vector models. The calculated depth-integrated velocity and Ψ-field agree well with earlier studies.     

铁路私有化席卷非洲大陆

非洲铁路实施特许权转让已经有10多年的历史。加拿大CPCS Transcom公司曾帮助非洲9个国家铁实施了路私有化改造。今天的经验来自历史的教训。     

Internet-based teleoperation platform for mobile robot

An Internet-based teleoperation platform for Mobile Robot is introduced in this paper. The hardware of the system mainly consists of a mobile robot. Its software employs client-server architecture for robot control and feedback information display . Different communication protocols are adopted according to the characteristics of message exchanged between the robot server and the client. The user interface is designed for the purpose of interaction. The great benefit of this client-server architecture is that the client software is insulated from the lowest level details of the mobile robot. Thus, it is very easy to implement and test new advanced teleoperation control algorithms, interface designs and applications on this platform without large programming work.