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Nowadays, shipyards are making every effort to efficiently manage their resources such as gantry cranes, transporters, and
block stock yards. The scheduling of block lifting for a gantry crane has been manually performed by an expert shipyard manager
for many years. Such a practice, however, can lead to an undesirably long time to produce scheduling plans. In addition, the
quality of the scheduling plans may not be optimal. To improve the overall process, a block lifting scheduling system for
a gantry crane was developed in this study by using optimization techniques. A block lifting scheduling problem was first
formulated as a multiobjective optimization problem. For a gantry crane, minimization of the traveling distance while unloaded
and wire and shackle replacement between block lifting was considered. An optimization algorithm based on the genetic algorithm
was then proposed and implemented so as to solve the problem. To evaluate the efficiency and applicability of the developed
system, the system was applied to an actual block lifting scheduling problem in a shipyard. Compared to results achieved by
manual scheduling by an expert manager, the results of this work show that blocks can be more efficiently lifted by a gantry
crane when the developed system is applied. 相似文献
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Young-Tae Chang Shu-Min Liu Hyosoo Park Younghoon Roh 《Maritime Policy and Management》2013,40(4):483-494
ABSTRACTNo studies have been conducted on cruise traveler expectations for a port of call in Asia. Current literature on general tourism shows that the research to measure traveler satisfaction is divided into two dominant approaches, the disconfirmation model, based on the Expectancy Disconfirmation Paradigm, and the perceptions-only model. However, previous disconfirmation models used different sample populations to measure traveler expectations and perceptions, resulting in biased results. The main objectives of this research was two-fold: (1) to develop a measurement scale for evaluating the expectations of cruise travelers during their visit to a port of call; and, (2) to examine the satisfaction of cruise travelers using the same sample population of the pre-visit expectations and post-visit experiences. The measurement scale for cruise travelers was developed using exploratory factor analysis and confirmatory factor analysis. Three factors, “Overall convenience/People,” “Culture/Exploration,” and “Commodities/Attractions,” were extracted from the analysis. Among these factors, the “Culture/Exploration” factor explained the largest part of overall satisfaction. The results also showed that the perception-only model outperformed the disconfirmation model in explaining overall satisfaction. Additionally, overall satisfaction was found to have a greater impact on the intention to recommend the visit to others than on the intention to revisit. 相似文献
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Taeksu Jung Yunhwa Hong Sungsu Park Cheongmin Kim Younghoon Hong Chongdu Cho 《International Journal of Automotive Technology》2018,19(2):281-289
Automotive brake noise has become a stubborn problem as automotive cars achieve higher driving torques, since that the increased torque induces the generation of severe noise dissipation during brake operation. Moreover, the global brake tuning market for achieving higher performance of the vehicle has expanded recently. The need to control the noise grows more in this connection. The tuning brake kits have employed cross-drilled and slotted machining pattern on the surface of the rotor. These designs have advantages to improve air ventilation, temperature control, and surface cleaning of brake pad. However, the effects of modal frequency by patterned rotor surfaces are rarely discussed, even if it is highly related with brake squeal phenomenon. Therefore, this study deals with the relationship between patterned surfaces and brake squeal through the numerical methods. The commercial software of a finite element analysis is employed for calculation by varying geometric design factors of each rotor pattern. As a result, the cross-drilled machining patterns are concluded to be an influential factor for in-plane mode frequency while the slotted patterns have more leverage for out-of-plane mode frequency. 相似文献
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