Simulation and Modelling - Old Questions

4. Explain about system, its environment and its components.

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

        Fig: Block diagram of system

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.