Order-picking operations constitute the costliest activities in a warehouse. The order-picking problem (OPP) aims to determine the route of the picker(s) in such a way that the total order-picking time, hence the order-picking costs are minimized. In this study, a warehouse that consists of parallel pick aisles is assumed, and various versions of the OPP are considered. Although the single-picker version of the problem has been well studied in the literature, the multiple-picker version has not received much attention in terms of algorithmic approaches. The literature also does not take into account the time taken by the number of turns during the picking route. In this thesis, a detailed discussion is made regarding the computational complexity of the OPP with a single picker. A heuristic procedure, which makes use of the exact algorithm for the OPP with no middle aisles, is proposed for the single-picker OPP with middle aisles, and computational results on randomly generated problems are given. Additionally, an evolutionary algorithm that makes use of the cluster-first, route-second and route-first, cluster-second heuristics for the VRP is provided. The parameters of the algorithm are determined based on preliminary runs and the algorithm is also tested on randomly generated problems, with different weights given to the cluster-first, route-second and route-first, cluster-second approaches. Lastly, a polynomial time algorithm is proposed for the problem of minimizing the number of turns in a parallel-aisle warehouse.

This thesis is a literature study on how existing research on embodied tool use may support the use of the use of the computer mouse within three dimensional environments, followed by an analysis of a typical scenario in the use of three dimensional environment. Problems with interaction in this domain are well known to designers of 3d programs but not well understood, which results in programs in which mouse controllers are used to control three dimensional objects being more difficult to learn and less efficient to use than would be possible if the interaction was better understood. The problems are often identified by their symptoms, such as the drag-threshold problem, picking problem, and the object rotation/viewpoint management problem, but this thesis will explore what the cause of those problems is, and identifies them all as a single cognitive problem which is found to be caused by a rift between the functioning of the two dimensional tool in use (the mouse and cursor) and the simulated three dimensional environment with which the cursor is interacting. Analyses are performed on a scenario, and result in a pinpointing of the problem and possible solutions to the interaction part of the problem (with design guidelines emerging), as well as finding the possibility that the cognitive roots of the problem result from an incompatibility between body-schema frames of reference for movement between the two dimensional parts of the action and the three dimensional part of the action.