Simulation and Modelling - Old Questions

4.  Define and describe different types of elements and components of a system.

A group of components which are interconnected and interact to fulfill certain objective is called a system. A system mainly consists of 4 elements: input, process, output and feedback.

        Fig: Block diagram of system

Input: It involves capturing and assembling elements that enter the system to be processed. Inputs to the system are anything to be captured by the system from its environment. For example, raw materials.

Processing: It involves transformation processes that convert input to output. For example, a manufacturing process.

Output: It involves transferring elements that have been produced by a transformation process to their ultimate destinations. Outputs are the things produced by the system and sent into its environment. For example, finished products.

Feedback:  It is the idea of monitoring the current system output and comparing it to the system goal. Any variation from the goal are then fed back in to the system and used to adjust it to ensure that it meets its goal. For example, data about sales performance is feedback to a sales manager.

A system boundary is a line that separates the system from the system environment. A change occuring outside the system may affect the performance of the system. Such changes are said to occur in the system environment. Therefore the system environment means anything outside the system boundary that may affect the system.

Components of the system

1. Entity: An entity is an object of interest for the purpose of the system study.

2. Attribute: The property or the characteristics of an entity is called attribute.

3. Activity: The time period of specified length is called activity. The activity changes the state of the system.

4. State: The state of a system is defined as the collection of variables necessary to describe the system at any time with respect to objectives of the study.

5. Event: The instantaneous occurance that may change the state of a system is called event. There are 2 types of event:

    a) Endogenous Event: The event that occurs within the system and change the state of the system is called endogenous event.

    b) Exogenous Event: The event that occurs outside the system but affects the state of the system is called exogenous event.