计量经济模型外文参考文献和翻译 第2页

issues that are associated with ship utilisation and maintenance. At about the same time Ye(1990) investigated equipment replacement with emphasis on the stochastic nature of maintenance and operating costs, but without allowing explicitly for the intricate interrelatedness of policies regarding utilization, maintenance and scrapping. In short, by concentrating on a few of the relevant decisions and ignoring the rest, all specialised and general purpose literature has adopted a partial equilibrium approach to study a problem, which is essentially general equilibrium in nature. For this reason the model that came closer to serving our research objectives is the one that has evolved from the contributions by Bitros (1976a, 1976b, 2004) and Bitros and Flytzanis (2002, 2003, 2004).
On the theoretical plain, the estimated model took a semi log-linear form and fitted well the observations. No matter how the data were segmented the estimates highlighted three key factors that explained total ship maintenance expenses in 1999. These were the age, the size and the utilisation of ships. In addition we estimated the effect on maintenance for vessels under 20 years old and for each type of vessel in the sample. The results confirm Frankel’s (1991) findings

2.1 A brief note on ship maintenance policies and regulations
In the period before the introduction of the International Safety Management Code
(ISMC), ship owners opted usually for a “breakdown” policy. In other words, all equipment would be lubricated and operated with care, yet no maintenance would take place until equipment would break down and it would require repairs or complete change of spares. This policy led to substandard vessels and coincided with a number of prominent shipping accidents (e.g. Exxon Valdez). As a result policy makers changed attitudes on how shipping maintenance should be done.
   The imposition of the ISMC and the increasing number of Port State Controls have
changed the disposition of shipping companies with respect the maintenance of ships. Nowadays any ISMC certified shipping company is obliged to carry a planned maintenance policy. Although some may be more organized than other shipping companies, the preventive nature of the new regulations imposes higher maintenance cost for all companies. In addition, the fact that planned maintenance work requires stricter control and existence of records has led to more frequent maintenance rather than postponing it until the next intermediate and special survey. ICS/ISF2 suggest that preventive maintenance policies be established for the non-exhaustive list of ship components shown in the Table 2.1. Actually the ISMC does not recommend an infrequent maintenance policy, but it imposes a continuous assessment of the vessel’s condition and requires immediate action by the shipping company to remedy any system fault or malfunctioning. VB实验室设备管理系统(论文+源码)
   Lastly, the increasing number of Port State Controls and Detentions of vessels has
obliged ship owners to be very careful on keeping good track maintenance records and to detect possible maintenance work before the ship entering a strict port on safety issues. Therefore,whenever it is practically feasible, ship companies increase maintenance work during a ship voyage,

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