用IBM磁盘阵列实现基于NT群集的电子邮件服务器

群集是使相互独立的一些系统作为一个整体工作,构成一个组.客户与群集相互作用时,群集像是一个独立的服务器,群集配置用于提高可用性和可缩放性.可用性(availability)是当群集中的一个系统发生故障时,群集软件迅速作出反映,将该系统的任务分配到群集中其它正在工作的系统上执行.群集技术使系统在故障发生时仍可以继续工作,将系统停运时间减到最小.群集也使企业内各自独立的服务器作为一个统一的系统,为未来的升级,增容提供了灵活性,(群集在计算机系统中具有重要的地位).……     

Public transport policy for central-city travel in the light of recent experiences of congestion charging

Excellent public transport which makes the private car a minority mode of central-city travel is a necessary condition for a political process towards the introduction of congestion charges. However, the charging system costs in London and Stockholm have proved to be unexpectedly high. Therefore, before these costs come down to an affordable level, zero-fares for central-city travel and stricter parking policy would be a first-best combination in many cities, always provided that the public transport is really competitive. A bold venture in public transport development is consequently the top priority irrespective of the transport pricing policy direction.     

用于碰撞测试的高速视频

目前，高速数字视频摄影术正用于汽车碰撞测试的诸多领域。采用适用于更快进程的高速视频，摄像机的最大帧率不断增长。与此同时，其硬件成本也在不断降低。     

Innovation,capabilities and competitive advantage in Norwegian shipping

As a high-cost country, it is believed that Norway has to build its competitiveness in most industries on innovation and knowledge-intensive products. The shipping industry is no exception. It has to be innovative in order to prosper. This unison conclusion, which has been drawn in several research projects during the last 10–20 years, is probably also applicable for companies in other high cost countries. A major issue in this research is how the industry can develop and maintain innovativeness and international competitiveness. The aim of this paper is to discuss the conclusion drawn in previous research concerning how the shipping industry can be innovative. It concludes that shipping companies have to improve their skills and competencies in a stronger interplay between organizations within and without the maritime cluster. This may increase their total capability and innovativeness and create distinctive competitive advantages that are difficult to imitate.     

Price and frequency competition in freight transportation

This paper develops a simple analytical model of price and frequency competition among freight carriers. In the model, the full price faced by a shipper (a goods producer) includes the actual shipping price plus an inventory holding cost, which is inversely proportional to the frequency of shipments offered by the freight carrier. Taking brand loyalty on the part of shippers into account, competing freight carriers maximize profit by setting prices, frequencies and vehicle carrying capacities. Assuming tractable functional forms, long- and short-run comparative-static results are derived to show how the choice variables are affected by the model’s parameters. The paper also provides an efficiency analysis, comparing the equilibrium to the social optimum, and it attempts to explain the phenomenon of excess capacity in the freight industry.     

Selfexcited Vibrations of the Tire

In this paper a mechanical work of external forces and torques, acting on the tire has been considered. A theory has been developed for the prediction of necessary conditions for selfexciting vibrations. The theory establishes, that the mechanical work of external forces and torques must be positive, or, what is equivalent, that the tire has to transmit energy from external environment to vehicle. The work of forces and torques has been considered as a convolution of functions, which next has been submitted to Laplace transformation. The condition of selfexcitation of vibrations, obtained from above in the frequency domain, establishes, that the imaginary part of all eigenvalues of frequency response matrix must be negative. As an example, the ranges of selfexcited vibrations of the tire have been calculated. The tire has been treated as a stretched circular string. Four different models have been considered. Three of them have been massles (kinematic), namely Pacejka's model, Von Schlippe's model and single-point model. As fourth model the dynamic Pacejka's model has been considered. The influences of longitudinal deflections on the shimmy tendency have been studied for all models

Frequency response characteristics have been numerically computed and compared for all models. A critical speed and a critical reduced frequency of first and second kind have been defined. Admissible, negative, imaginary parts of the eigenvalues of frequency response matrix have been established. These admissible values of imaginary parts of eigenvalues assure, that the energy absorbing does not excite shimmy vibrations.     

Benzene concentrations on board chemical tankers

Maritime transport of benzene is regulated by the International Maritime Organisation (IMO). Two important guidelines for a ship’s crew in this matter are IMO circulars 1095 and 1220. The first one describes the minimum safety standards for ships carrying liquids in bulk containing benzene while circular 1220 deals with structural guidelines for new ships carrying liquids in bulk containing benzene, but also technical developments could help in improving safety and health protection on board chemical tankers carrying benzene in bulk. The aim of the present paper is to determine the benzene concentration in the working and living environment on board a modern chemical tanker carrying benzene in bulk, where all safety, technical and operational procedures described by IMO in the above-mentioned circulars are followed. During specific cargo operations, we measured the benzene concentrations on different locations on board by means of Radiello® passive diffusive samplers. Despite all measures taken, we found an important difference in benzene concentration between operations with a benzene cargo compared to operations without benzene on board, as well as inside and outside the accommodation. Moreover, even during discharge operations, where the emission is theoretically zero, we found an important increase in the benzene concentration. In addition, we found less favourable results for the engine room.     

An algorithm for combining autonomous vehicles and controlled events in driving simulator experiments

Autonomous vehicles can be used to create realistic simulations of surrounding vehicles in driving simulators. However, the use of autonomous vehicles makes it difficult to ensure reproducibility between subjects. In this paper, an effort is made to solve the problem by combining autonomous vehicles and controlled events. A controlled event can be compared to a theatre play. The aim is to achieve the same initial play conditions for each subject, which can be problematic since the traffic situation around the subject will be dependent upon each subject’s actions while driving in autonomous traffic. This paper presents an algorithm that achieves the transition from autonomous traffic to a predefined start condition for a play. The algorithm has been tested in the Swedish National Road and Transport Research Institute (VTI) driving simulator III with promising results. In most of the cases we examined the algorithm could reconstruct the specified start condition and conduct the transition from autonomous to controlled mode in a inconspicuous way. Some problems were observed regarding moving unwanted vehicles away from the closest area around the simulator vehicle, and this part of the algorithm has to be enhanced. The experiment also showed that the subjects drove faster in the presence of controlled everyday life traffic normally used in the VTI driving simulator than in autonomous traffic.     

Evaluating CO2 emissions, cost, and service quality trade-offs in an urban delivery system case study

Growing pressure to limit greenhouse gas emissions is changing the way businesses operate. This paper presents the trade-offs between cost, service quality (represented by time window guarantees), and emissions of an urban pickup and delivery system under these changing pressures. A model, developed by the authors in ArcGIS, is used to evaluate these trade-offs for a specific case study involving a real fleet with specific operational characteristics. The problem is modeled as an emissions minimization vehicle routing problem with time windows. Analyses of different external policies and internal operational changes provide insight into the impact of these changes on cost, service quality, and emissions. Specific consideration of the influence of time windows, customer density, and vehicle choice are included.The results show a stable relationship between monetary cost and kilograms of CO₂, with each kilogram of CO₂ associated with a $3.50 increase in cost, illustrating the influence of fuel use on both cost and emissions. In addition, customer density and time window length are strongly correlated with monetary cost and kilograms of CO₂ per order. The addition of 80 customers or extending the time window 100 minutes would save approximately $3.50 and 1 kilogram of CO₂ per order. Lastly, the evaluation of four different fleets illustrates significant environmental and monetary gains can be achieved through the use of hybrid vehicles.The results demonstrate there is not a trade-off between CO₂ emissions and cost, but that these two metrics trend together. This suggests the most effective way to encourage fleet operators to limit emissions is to increase the cost of fuel or CO₂ production, as this is consistent with current incentives that exist to reduce cost, and therefore emissions.     

The estimation of transport cost functions: a methodological review

Abstract

The ex‐post facto cost of using private finance in roads is examined using a case study approach. The paper focuses on the first eight design, build, finance and operate (DBFO) roads commissioned by the UK Government’s Highways Agency and paid for through a system of shadow tolls. It carries out a financial analysis of the publicly available accounting information from the Highways Agency and its private sector partners for the first 6 years since the start of the 30‐year schemes in 1997. Publicly available financial information about the schemes was found to be limited and opaque. In 3 years, the Highways Agency had paid more than the construction cost. It was unclear whether the payments were higher than expected at financial close. Its private sector partners reported a post‐tax return on capital of 29% and an effective cost of capital of 11% in 2002, twice the cost of public finance. However, operating through a complex web of subcontracting creates additional, undisclosed sources of profit for their parent companies that make it difficult to establish the total cost of using private finance. The paper questions the wisdom of using private finance by providing evidence about the cost, including the cost of risk transfer.