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Title: Aspects of container loading
Author: Ratcliff, Max Simon William
ISNI:       0000 0004 2715 6224
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1996
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This work deals with the problem of container loading. It analyses the effectiveness of a layering approach to the problem. The approach is applied to three key areas within this field, the first being concerned solely with the production of efficient, yet stable, loading arrangements for a single container. Using this as a foundation, subsequent work considers the handling of certain practical aspects. The third area of research concerns extensions to the approach in order to tackle situations where all of the cargo needs to be stowed in a set of (several) containers. The work demonstrates that the proposed approach produces packing arrangements which are highly efficient in terms of volume utilisation, and are generally superior to results obtained from a variety of other approaches. Several modified versions of the approach are presented, but it is shown that the original algorithm (with some enhancements of secondary importance) provides a better basis for further work. Where separation of the cargo is required, e.g. when it consists of consignments for different destinations, the layering approach has some limitations. A method of column building, which overcomes these shortcomings, is presented and is shown to be complementaty to the layering approach in terms of the packing efficiency obtained. However, this method has severe drawbacks in relation to load stability. It is shown that practical criteria such as load-bearing ability of boxes and preferences relating to direct contact placements can be incorporated into the layering approach. The method developed uses opportunity cost concepts to govern the placement of boxes. It is demonstrated that the method can produce a significantly higher packing efficiency than is achieved when weight considerations are treated solely as constraints. A system of 'finetuning' is presented that allows the criteria involved to be given user-defined weighting factors. This is shown to be significantly enhanced by a mechanism which checks whether weight aspects are relevant in the current step of the algorithm. This research also demonstrates that the problem of loading multiple containers can often be optimally solved by using one of a number of techniques based on the single container layering approach. Sequential methods, in which containers are loaded one after another by the application of a single container algorithm, are examined. These are compared with procedures where simultaneous consideration is given to the loading of several containers. A computationally more complex method, based on a set covering philosophy, is also investigated as a possible approach. 'This process involves the generation of a number of single container loading configurations and subsequent selection, by integer programming, of a minimal subset which covers the total consignment. The potential of this type of approach is clearly demonstrated
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available