Quantifying uncertainty in high-resolution coupled hydrodynamic-ecosystem models

Marine ecosystem models are becoming increasingly complex and sophisticated, and are being used to estimate the effects of future changes in the earth system with a view to informing important policy decisions. Despite their potential importance, far too little attention has been, and is generally, paid to model errors and the extent to which model outputs actually relate to real-world processes. With the increasing complexity of the models themselves comes an increasing complexity among model results. If we are to develop useful modelling tools for the marine environment we need to be able to understand and quantify the uncertainties inherent in the simulations. Analysing errors within highly multivariate model outputs, and relating them to even more complex and multivariate observational data, are not trivial tasks. Here we describe the application of a series of techniques, including a 2-stage self-organising map (SOM), non-parametric multivariate analysis, and error statistics, to a complex spatio-temporal model run for the period 1988–1989 in the Southern North Sea, coinciding with the North Sea Project which collected a wealth of observational data. We use model output, large spatio-temporally resolved data sets and a combination of methodologies (SOM, MDS, uncertainty metrics) to simplify the problem and to provide tractable information on model performance. The use of a SOM as a clustering tool allows us to simplify the dimensions of the problem while the use of MDS on independent data grouped according to the SOM classification allows us to validate the SOM. The combination of classification and uncertainty metrics allows us to pinpoint the variables and associated processes which require attention in each region. We recommend the use of this combination of techniques for simplifying complex comparisons of model outputs with real data, and analysis of error distributions.     

谐波对牵引变压器损耗的影响

根据一个牵引变压器的损耗,提出了谐波对绕组电阻的影响.对同心式和饼式线圈的变压器进行了分析.使用二维有限元计算软件"Flux2D"进行了多种仿真,并且将其结果与实际变压器测量值进行对比,提出一个简单的定律,由此可确定2种不同类型变压器电阻随频率的变化规律.     

Validation of a schedule‐based capacity restraint transit assignment model for a large‐scale network

This paper describes the application of a capacity restraint trip assignment algorithm to a real, large‐scale transit network and the validation of the results. Unlike the conventional frequency‐based approach, the network formulation of the proposed model is dynamic and schedule‐based. Transit vehicles are assumed to operate to a set of pre‐determined schedules. Passengers are assumed to select paths based on a generalized cost function including in‐vehicle and out‐of‐vehicle time and line change penalty. The time‐varying passenger demand is loaded onto the network by a time increment simulation method, which ensures that the capacity restraint of each vehicle during passenger boarding is strictly observed. The optimal‐path and path‐loading algorithms are applied iteratively by the method of successive averages until the network converges to the predictive dynamic user equilibrium. The Hong Kong Mass Transit Railway network is used to validate the model results. The potential applications of the model are also discussed.     

MBS(R)--欧洲制动控制系统平台

克诺尔机车车辆制动公司开发了模块化的标准制动控制系统MBS,只需较少的费用就可适应欧洲铁路运输企业的各种不同要求.制动系统必须按用户的专门要求来开发.可适配的模块化MBS系统可用于欧洲各国的跨境运输,能满足欧洲不同的安全性规定.系统具有重量轻、所需安装位置小、寿命周期费用低、机车车辆使用率高的优点.Bombardier公司、德国铁路公司、瑞士和奥地利联邦铁路已从中获益.     

车轮踏面剥离试验研究

剥离是车轮踏面失效的主要类型。车轮剥离一般分为2种类型,一类是由滚动接触疲劳应力作用引起的剥离;另一类是由热作用和机械作用引起的剥离,主要有制动剥离和擦伤剥离。2种类型的车轮剥离实际上都与轮轨表面摩擦力直接相关。本文主要通过模拟试验研究轮轨摩擦力对车轮剥离的影响。     

Insights into the port training of the new European Union member states 1

The establishment and implementation of a training programme requires a training needs assessment (TNA). Without this approach, more often than not, training programmes have failed to succeed and to make such an assessment the instructional designer, i.e. the person in charge for this work, needs to follow a methodology. Unlike the other industries, the port industry has neglected the use of these methodologies, which is shown by the lack of research work published in academic journals. With a view to fill the existing gap, the paper proposes a five-step TNA methodology to be used in the port industry and applies its first three steps to investigate the port training situation in the new European Union member states. To achieve this objective, the paper is structured in the following way: puts the research work into context; addresses the role of ports; presents a port TNA methodology; explains research methodology; addresses port training issues in the new European-member states; and presents conclusions and further comments.     

Shipping and investment incentives: a trilogy Part 2. Investment incentives for shipping

This paper concentrates on the shipping industry and considers the forms of fiscal and financial incentives which are used by different governments to promote or encourage investment in their shipping industry. The analysis reduces the various packages of investment incentives and loan arrangements to a common measurement—the net present value of the package—and uses this to draw international comparisons and rankings. The results are based on different values of rates of return in the shipping industry and under certain assumptions concerning the rate of inflation and the rate of discount. Differences in loan arrangements have also been incorporated. The particular results are valid only for the specified circumstances but the methodology is generally applicable.     

Sail–sail and sail–hull interaction effects of hybrid-sail assisted bulk carrier

In a previously reported study, wind tunnel experiments were undertaken to investigate the aerodynamic characteristics of hybrid-sails in isolation. Such sails are seen as providing a worthwhile reduction in the delivered power to the propeller and hence the engine generated thrust, with a corresponding reduction in the CO₂ production of diesel engine exhaust. In this paper, wind tunnel testing is used to investigate sail–sail interaction effects for two sets of four identical hybrid-sails, and the sail–hull interaction effects for the same two sets of four identical sails in the presence of a bulk carrier hullform. The analysis presented suggests that to build a sail-assisted ship requires an appreciation of the sail–sail and sail–hull interaction effects.     

Hydrographic cruises off northwest Africa: the Canary Current and the Cape Ghir region

We present hydrographic data for several sections located along the African coastline and off Cape Ghir, carried out at times of weak surface winds (October 1995 and September 1997). The main sections are near the continental slope, at mean distances between 100 and 150 km from the coastline. North of Cape Ghir (31°N) the geostrophic transport (referenced to 650 m) of North Atlantic Central Water through these sections is 3.7 and 2.0 Sv for 1995 and 1997, respectively. This confirms that a major fraction of the water transport by the Canary Current flows east, into the continental slope off northwest Africa, at latitudes above Cape Ghir. Most of this flow continues south past Cape Ghir, along the coast and probably through the eastern passages of the Canary Archipelago. A significant fraction, however, may escape through surface Ekman transport (0.3–0.5 Sv during the early fall season) and by offshore flow at Cape Ghir (1.1 Sv in September 1997, referenced to 650 m). Despite the weak winds the Cape Ghir filament was clearly visible, characterized by localized coastal upwelling associated to a cyclonic shallow structure and cold (and fresh) waters stretching offshore as a very shallow feature (50–100 m deep). The satellite images show that the surface temperature field is highly variable, in rapid response to the surface winds, always with a core region of relatively cold water and commonly with one or two associated eddies. Our results support the existence of two recirculation cells in the area: a horizontal one that connects the interior eastern boundary currents with the coastal region and a vertical one related to both wind-induced and filament upwelling. The data also show a salinity subsurface maximum at the root of the filament, linked to water inflow from northern latitudes, and a subsurface anticyclonic eddy over the Agadir canyon, likely related to the poleward slope undercurrent.     

The simple,compelling case for PRT

When compared with existing urban modes, Personal Rapid Transit (PRT) offers compelling advantages in every important respect. The desirable attributes of any urban mobility mode are well documented, such as minimal travel time, safety, comfort, low cost, and minimal impacts. These attributes are used to define a hypothetical, ideal urban mode. The ideal mode would possess characteristics such as no waiting, no stops, from anywhere to anywhere service, risk-free, non-polluting, and accessible to everyone at any time. Although not attainable in the real world, the ideal provides a model and benchmark for design much as the Carnot thermodynamic cycle guides the development of internal combustion engines, or ideal gases and perfect fluids are postulated in physics. A matrix format is used to present the characteristics of various modes against the desirable attributes of any mode. Modes presented are the ideal, walking, bicycles, motorcycles, automobiles, taxis, buses, rail transit, Automated Guideway Transit (AGT), and PRT. In all respects, PRT is shown to approach the ideal much more closely than competing modes.