尾气净化前后的对比检测

马克带着5气体分析仪来到公路上,向我们说明对净化前的尾气进行检测是探测发动机状况的好方法。     

The influence of qualitative factors in Isle of Man ship registration decisions

Open registers have developed in recent years as an economic necessity allowing costs to be cut in response to an over-tonnaged marketplace where low to nonexistent profit margins were the norm under the registers of the traditional maritime nations. These open registers allow shipowners the flexibility to reduce their operating costs by, for example, employing cheap foreign crews. The majority of studies in this area have concentrated, quite rightly, on the economic reasons why shipowners flag-out to registers other than their home register. There are, however, a number of more nebulous reasons why shipowners choose one open register as opposed to another. This paper presents the results of a survey which attempts to deduce these qualitative influences over register choice. The specific context of the Isle of Man register is used to illustrate the importance of such factors.     

Nature or nurture: why do railroads carry greater freight share in the United States than in Europe?

During the 1950s, the share of freight carried by railroads was similar and declining in both the United States and Europe. By 2000, the railroads’ share of freight (measured in ton–kilometers) had reached 38% in the United States while falling to 8% in Europe. This paper examines the reasons for the difference in rail’s share of freight in Europe and the United States. We find that almost 83% of the gap in 2000 is probably due to natural or inherent differences, principally geography, shipment distance, and commodity mix. However, 17% of the gap cannot be explained by these inherent differences and is presumably due to public policies including priority of passenger service, lack of interoperability at borders, service quality and rates, and incentives of the rail operators. We estimate that if that policy gap were closed, railroads’ share of freight in Europe would increase from 8% to 13%.