In this paper, we analyze a practical situation in which an inventory manager is faced with several options to store excess stocks whenever the storage capacity of his/her warehouse is insufficient. The manager can choose from either storage space providers through fixed long term or flexible leasing contracts, or the manager can acquire the extra required space from the spot market. We formulate this inventory problem with multiple storage facilities as a nonlinear program and show that it has a global optimal solution. We then provide closed-form solutions for the optimal ordering quantity and leased spot market space depending on the value of the unconstrained economic order quantity. In addition, we develop some structural properties for the optimal ordering policy and include several examples to illustrate the formulated models. 相似文献
The sports scientist and the ergonomist, although sharing a common disciplinary background, pursue fundamentally different goals. The patterns of approach to the analysis of movement they adopt are, nevertheless, similar and a model of this approach is presented. Some potential sources of error associated with each stage of the process are identified.
In measuring motion in sport, cinematography has played a dominant role. The method has obvious advantages; but analysing film is a slow, pedestrian task, and subject to human error. Where an investigator is experienced and understands his problem clearly he can often achieve his aims with a limited number of measurement variables. This may also meanhe can adopt automatic and specific techniques of acquiring information. Such methods include alternative photographic techniques, but also involve the specialised transducers and automatic analysers that are now burgeoning in the field. Some of these techniques are discussed. 相似文献