Analyzing trade-offs between transportation,inventory and production costs on freight networks

The purpose of this paper is to determine optimal shipping strategies (i.e. routes and shipment sizes) on freight networks by analyzing trade-offs between transportation, inventory, and production set-up costs. Networks involving direct shipping, shipping via a consolidation terminal, and a combination of terminal and direct shipping are considered. This paper makes three main contributions. First, an understanding is provided of the interface between transportation and production set-up costs, and of how these costs both affect inventory. Second, conditions are identified that indicate when networks involving direct shipments between many origins and destinations can be analyzed on a link-by-link basis. Finally, a simple optimization method is developed that simultaneously determines optimal routes and shipment sizes for networks with a consolidation terminal and concave cost functions. This method decomposes the network into separate sub-networks, and determines the optimum analytically without the need for mathematical programming techniques.     

不同结构的径向转向架与普通转向架之理论比较

比较了不同结构径向转向型与普通2轴转向架间的动力不.折重点是直线稳定性，曲线轮轨横向力和轮轨磨耗指标等参数。其结果表明，所研究的径向转向架结构在一般应用范围内，没有比普通转向架起到更好的作用。但在特殊运行条件下和某些应用形式中，某些径向转向架比普通转向架更具优势。     

轮轨系统中使用直线电动机技术的可能性

德国铁路为提高现有以及今后动车的功率,研究了轮轨系统中使用直线电动机技术的可能性.首要的问题是,用直线电动机产生的附加切向力提高牵引力.接着的另一个项目是,研究直线电动机产生的附加法向力分量是否能提高传递到轮轨接触点上的牵引力或制动力,以及是否能降低轻型导向的端部控制车对侧风的敏感性.     

An analysis of the Brazilian ship financing system

The Brazilian ship financing system has some unique features. The funds made available to finance the construction and acquisition of ships are sourced from a tax on import and cabotage freight, payable by the shippers. For Brazilian flagged ships, a portion of the tax generated can be used for the payment of loan instalments. This paper analyses the impact of the tax on the economy as a whole, and discusses the distribution of the tax burden between the shipowner and the shipper, taking into account the maritime transport demand elasticities in Brazil. The paper also analyses the effectiveness of the financing system in reducing the capital cost to shipowner, and the distortion effects produced by the utilization of the tax in loan repayments. The conclusion is that there are important distortions that may threaten the recovery of the maritime industry in Brazil.     

电解电容器温度函数模型的研究

电解电容器具有容量大和价格低的优点,常用于电力电子的诸多领域,主要功能为滤波和储能.其特性受频率和温度变化的影响较大.在电气仿真软件中一般不考虑温度变化的影响,而在运输、工业、航空或军事等许多领域中,温度变化的影响却有着显著的重要性.因而建模时有必要将该变化纳入考虑范围.在该研究中,我们在定义此简易模型时,依据温度和频率的变化考虑了电解电容器的特性变化,并基于遗传算法提出了识别方法,在简易性和精确度之间进行折衷是本研究的目的.对额定值为4 700 μF/500 V的大功率电解电容器进行了鉴定.对测量值和不同温度下的模型进行了比较,结果令人满意.相比标准模型,该模型对0℃以下温度有更精确的计算.此外,由于该模型中使用的元件数量受到了限制,因而考虑在仿真软件中进行简单集成.     

The design of tram priority at traffic signals

This paper outlines the guidelines being used to introduce tram priority at traffic signals in Melbourne. Where techniques being used to meet the guidelines are of interest they are briefly outlined. Similarly, where it has been found that it is not possible to meet the full requirements of the guidelines, the deficiencies of current techniques are outlined and areas for further investigation put forward.     

The effects of non-optimal pricing and investment policies for transportation facilities

A simulation model was used to show the impacts of non-optimal pricing and investment timing policies for a major airport and an urban expressway. It was found that: the losses of economic surplus due to non-optimal pricing and investment policies were relatively small (less than 1% of the net present value of economic surplus for optimal pricing and investment), that marginal cost pricing covers the capital cost of all but the first increment of capacity, that higher user fees will permit the facilities to break even with relatively small losses of economic surplus, that marginal cost pricing has some effect relative to existing pricing policies in delaying the dates new capacity is required and achieving better capacity utilization, and that the shape of the cost function has a substantial impact on the amount of capacity required.     

SiMoCo: the viability of a prototype platform for a coastal monitoring system: a case study

Coastal zones are among the most productive areas in the world, offering a wide variety of valuable habitats and ecosystems services. Despite the low population density in the Brazilian coastal zone, their distribution is quite concentrated near some coastal cities and state capitals. This concentration places enormous pressure on coastal resources. Therefore, the main objective of this paper is to present an overview on the current status of SiMoCo (Sistema de Monitoramento Costeiro, or Coastal Monitoring System in English) project as a possible early warning system that can be integrated to the Brazilian Coastal Management Information System. This prototype platform provides a real-time access to the composition, organization and simulation of planktonic communities. First, our results demonstrate such a system detecting a target dinoflagellate; second, we apply structural and functional indexes to compare and characterize the ecological networks from two different coastal areas. Conclusions are made about SiMoCo’s feasibility and its possible contribution to the decision-making process within integrated coastal zone management (ICZM) strategies.