微波除冰关键技术及应用前景分析

由冻雨形成的冰层由于与路面粘结强度大，普通除冰除雪机械无法清除，微波除冰技术可以对冰层与路面接触处进行加热，使冰层与路面分离，实现快速除冰。但是微波除冰技术的应用存在微波利用率低，设备复杂等难点。对钛酸钡加入沥青混凝土之后的微波吸收效率进行了试验，得知加入钛酸钡后混凝土对微波的吸收效率有明显提高，并指出微波除冰技术的研究应该注意微波加热设备的灵活利用和将微波除冰技术纳入综合除冰除雪体系。     

Efficiency of urban public transit: A meta analysis

The aim of this paper is twofold. First, to provide a statistical overview of the literature on public transit efficiency performance. Second, to statistically explain the variation in efficiency findings reported in the literature. To this end, first some key concepts of efficiency analysis will be introduced, while next the different frontier methodologies that are used in the literature will be discussed. The empirical part of this paper consists of a statistical summary of the literature as well as meta-regression analyses for different samples of the literature in order to identify key determinants of technical efficiency (TE) of public transit operators. For a broad sample of observations, we found significant and consistent effects of the type of database, region and output measurement method. For the sample of non-parametric studies we found that the type of frontier assumptions also have an impact on the efficiency ratio. Further results show that there is no statistical difference in TE ratios between parametric and non-parametric studies. Finally, we found a positive univariate relationship between the number of inputs in the estimated specification and the efficiency ratio.     

Future air traffic management systems and financial decision-making constraints

The object is to identify characteristics of feasible systems for UK – and European – Air Traffic Management (ATM) in the coming decades. ATM here covers Air Traffic Control (ATC) provision plus wider issues, such as airspace design. The analytical focus is on the financial decision-making processes and constraints that will act to shape this future system. R&D work into control workload and planning based on an "ATM core concept" are proposed as likely to offer the best way forward.     

多缸汽油机进气瞬态性能的研究

本文利用所建立的进气模型，对火花点火式发动机的进气特性进行了数值和分析。结果表明所采用的研究方法具的较高的实用价值，文中还对火花点火式发动机的各缸进气不均匀性和不均匀偏和了研究，为改善发动机缸内燃烧过程的均匀性提供了有效的方法。     

The operation of Swedish motor-vehicle inspections: efficiency and some problems concerning regulation

Efficiency in the operation of the Swedish motor-vehicle inspection monopoly was examined by analyzing data on all decision-making units related to production of inspection services during 1993. In addition, theoretically based arguments concerning some regulation problems are discussed. The results imply a fairly high level of technical efficiency, which might be explained by the extensive practice of yardstick-competition in the industry. The findings, based on a best-practice approach, do not indicate strong empirical evidence in support of a deregulation of the industry. However, the regulation problems discussed may provide motives for deregulation.     

Productivity,efficiency and technical change in the European railways: A non-parametric approach

The purpose of this paper is to analyse the evolution of productivity in the European railways in the period 1970–95. We use a non-parametric approach that enables changes in productivity to be broken down into variations in efficiency and technical change. The results indicate that the productivity growth is concentrated in the last period (1985–95), when the majority of the companies undertook processes of reforms. This increase in productivity is mainly due to technical progress. We also analyse the determinants of efficiency and, unlike other papers, the technical change, finding that the greater the degree of autonomy and financial independence, the higher the efficiency levels and technical change. This revised version was published online in June 2006 with corrections to the Cover Date.     

提高阻挡大型机动车辆路障效率的研究

随着当今世界各国对安全的重视和汽车炸弹恐怖袭击的层出不断,防恐机动车阻挡路障的研究和应用成为重要课题。本文主要针对阻挡大型高速货车类车辆的路障进行了试验研究,利用LS-DAYNA建立了和试验结果吻合的有限元模型。参考美国DOS(Department of State)标准关于机动车阻挡路障的要求,通过模拟计算方法研究了如何提高对大型高速车辆的阻挡效率、减少车辆穿过路障距离的方案。模拟和试验表明,所提方案可以有效地阻挡大型车辆,对提高我国相关产品的性能并使之与国际标准接轨有重要指导作用。     

CO2 efficiency in road freight transportation: Status quo, measures and potential

Road freight transport continues to grow in Germany and generates 6% of the country’s CO₂ emissions. In logistics, many decisions influence the energy efficiency of trucks, but causalities are not well understood. Little work has been done on quantifying the potential for further CO₂ reduction and the effect of specific activities, such as introducing computer assisted scheduling systems to trucking firms. A survey was survey out and linked fuel consumption to transport performance parameters in 50 German haulage companies during 2003. Emission efficiency ranged from 0.8 tonne-km to 26 tonne-km for 1 kg CO₂ emissions. The results show potential for improvements given a low level of vehicle usage and load factor levels, scarce use of lightweight vehicle design, poorly selected vehicles and a high proportion of empty runs. IT-based scheduling systems with telematic application for data communication, positioning and navigation show positive effects on efficiency. Fuel use and transport performance was measured before and after the introduction of these systems.     

The analysis of regulation on private highway investment under a build-operate-transfer scheme

The build-operate-transfer (BOT) approach has become an attractive instrument for public facility provision, especially for a project that faces difficulty with public finance. This study analyzes the regulation alternatives on private highway investment under a BOT scheme and their impacts on traffic flows, travel costs, toll, capacity, and social welfare (total user-benefit in the traffic system including congestion). For comparison, five cases are analyzed: (1) No BOT with maximizing welfare, (2) No BOT with breaking even on finance, (3) BOT without regulation, (4) BOT with a minimum flow constraint (the total users will not be less than those in Case 1), and (5) BOT with a maximum travel cost constraint (the travel cost for users on a non-tolled road will not exceed the maximum tolerance). After each case is modeled and simulated on some functional forms, we find that the case of BOT with regulations performs between the cases of maximizing welfare and that of maximizing profit. From the perspective of the government, regulation has less power in a project with low elastic demand. Furthermore, even when the regulation is strict, a high cost-efficient firm with BOT could result in a higher level of social welfare than that without a BOT scheme.     

RV传动的研究

RV传动是在摆线针轮行星传动的基础上发展起来的一种新型传动。本文分析了RV传动的原理、特点、效率及结构,较深入地研究了RV传动在运转的不同位置的受力分析。