Dynamics in Logistics

Queues v System Dynamics In a system there are different entities that are flowing into and accumulate in stocks then they flow out sometimes into another stock. This is just the same as items in a queue or waiting line. However there are some aspects which are different from queue when compare to systems dynamics. Queues are different from the items that are flowing in and out of stocks as characterized by system dynamics. System dynamics construct normally allows for modeling of continuous events and bringing in system feedback.

System dynamics is thus a methodology that is used in the understanding of how systems work over time. There are two types of systems the open and feedback systems. An open system is one that takes inputs and produces an output from them which does not have any impact on future inputs. On the other hand a feedback system is one that uses the outputs of one cycle in order to influence the inputs for decision making in future cycles.

There are several examples of items that flow using a system dynamic model. One example is savings and interest accumulated on the savings. Savings is a level whereas interest is a decision function which is represented by the valve in system dynamics. The valve is what controls the rate of flow into the savings from the interest. The interest is normally dependent on the current levels of savings and interest rates. The interest normally causes the rate to change when it comes to amount of savings.

A second example is a manufacturing company whereby the rate of production is dependent the supply of raw materials. If there are no raw materials then the production can not go on (Aitelli, & Deckro, 2004). Queuing theory is the study of contention when it comes to using shared but limited resources. It is made up of models and formulas which give a description of the relationship between service requests, delay and congestion.

There are several examples of how queuing theory can be applied one is in a post office where there is one line but with several clerks the net person who will be served is the one that has stood longest within a line. The burden of the wait is thus shared by all those people that are found within the line the longer a line is then the longer the wait will be.

A second example is trucks that are entering a dock; they have to be within a queue so that they can be order during the process of clearing. It would be chaotic if everyone would want to be served without following a queue.

On the basis of average arrival rates and average service rates there are formulas that describe queuing models can be used for the calculation of important system measurements like capacity utilization, average waiting times for servicing of average number of items that are to be in a queue at any particular time. The nature of the.