船体分段制造日程计划的模拟与优化

本文分析了国内外对分段制造日程计划的研究状况,得到了适合中国国情的研究思路。提出了分面制造日程计划的模拟与优化方法,包括年生产计划的分解、构造排序函数、分段进出场地的规则,提出了优化的目标函数,以若干艘相同的７万吨级散货船为对象组成一年造船计划,以上海一造船厂为模拟船厂,用Ｄｅｌｐｈｉ编制程序,实现了计划的模拟,并能达到优化。经计算证实本文提出的方法是可行的。     

对Flowshop排序问题启发式方法的评价与改进

本文在对Flowshop排序问题的几种主要启发式方法进行深入剖析的基础上,提出了一种新的启发式方法,这种方法不仅简单实用,工作量小,能迅速求得排序问题的解。而且优度较高,能得到近似最优的排序方案。     

Modeling and analysis of panel hull block assembly system through timed colored Petri net

To implement efficient production control, this paper provides a timed colored Petri net (timed CPN) approach to performance modeling, real-timed dispatching and simulation of Panel hull block assembly system (PHBAS). The definition of Petri net is extended to accord with the real-world PHBAS’s organization, and the modeling method for hull flow production is provided in order to simplify modeling program. Using modeling and analyzing method, the dynamic characteristics of the system can be emulated and quantitatively calculated and work control tactics can be optimized. For the double bottom hull block shipbuilding system in a recently built shipyard in China, the simulation model with timed CPN was described and the system parameters and optimal task sequence which has the minimum operation time were obtained for a scheduling case.     

The value of travel time variance

This paper considers the value of travel time variability under scheduling preferences that are defined in terms of linearly time varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can freely choose departure time and to travellers who use a scheduled service with fixed headway. Depending on parameters, travellers may be risk averse or risk seeking and the value of travel time may increase or decrease in the mean travel time.     

Additive measures of travel time variability

This paper derives a measure of travel time variability for travellers equipped with scheduling preferences defined in terms of time-varying utility rates, and who choose departure time optimally. The corresponding value of travel time variability is a constant that depends only on preference parameters. The measure is unique in being additive with respect to independent parts of a trip. It has the variance of travel time as a special case. Extension is provided to the case of travellers who use a scheduled service with fixed headway.