Decision Support System ICS425

Decision Support System ICS425 Unit 6 Operation Research Queuing Systems

Operation Research • The following stages could be identified for Operation Research (OR) project: • Formulating the problem • Constructing the model • Deriving a solution • Testing the model and evaluating the solution • Implementing and maintaining the solution

Operation Research • OR has been applied to a wide variety of problems • Most of problems have been tactical rather then strategic in nature • An important consequence of the application of OR to a wide variety of tactical problems is that a small set of problem types has been identified which accounts for most of these problems

Operation Research • Prototype Problems; • Inventory • Allocation • Queuing • Sequencing and coordination • Routing • Replacement • Competitive • Search

Inventory • Involve what is apparently the simplest operation that can be conceived – holding or sorting resources. • The decisions required generally entail the determination of how much of a resource to acquire or when to acquire it. • e.g. the determination of how many of each of a large number of parts to purchase or produce, and when to do so.

Allocation • The task to allocate the available production facilities to the jobs to be done in such a way as to minimise the losses that result from not being able to carry out the solution to the inventory problem originally considered in isolation. ( if it is apparent there are not enough facilities to produce all the items specified in the solution in inventory problem)

Allocation • The solution of the allocation problem is usually based on a model in which facilities are assumed to be available without interruption. ## It may become apparent that the allocation of facilities should take these possible delays into account. To do so requires solving a -> queuing problem

Queuing • Queuing model generally assume a rule for selecting the next among the things/jobs waiting for service on which work will be done • In some cases the order in which these jobs are carried out has a significant effect on the total time required to do all of them or on the distribution of completed times around the dates on which they are due.

Queuing • The research may be required to find that sequence in which the jobs should be done so that some objective expressed in terms of total time or completion times is met.

Routing & Replacement • If equipment or men must be prepared (set up) for doing each job of a set and if the amount of preparation depends on the order in which the jobs are done, set-up costs as well as time considerations may have to be taken into account • To do so involves solving a routing problem

Routing & Replacement • If this problem were considered over an extended period of time, it would be necessary to consider the replacement of equipment that is wearing out or is worn out

Competitive • Up to this stage in the development of the problem we have been concerned almost exclusively with the behaviour of the system under the study, not with the behaviour of outside parties who affect the organization’s performance, such as suppliers, customers, or competitors.

Competitive • If their behaviour is taken into account in attempting to purchase materials at lower price, for example, or to sell more or better price, a competitive problem is involved.

Search • Problems that involve the determination of how much and what information to acquire, how to acquire it, and how to treat it once it has been acquired, are search problems • It should be apparent from this discussion that management problems can seldom be isolated from one another.

Descriptive & Explanatory Model • It is important to distinguish between models; • that contain controlled variables • And, those that do not. In general, those that do are explanatory and those that do not are descriptive It is frequently necessary to construct descriptive models as a preliminary step towards developing an explanatory decision model

Decision Support System ICS425