What is Simulation ?
Meaning and Definition of Simulation :
A simulated model may be defined as one which depicts the working of a large scale system of man, machines, materials and information operating over a period of time in a simulated environment of the real world conditions.
Simulation is a numerical solution method that seeks optimal alternatives (strategies) through a trial and error process. The simulation approach can be used too study almost any problem that involves uncertainty, i.e., one or more decision variables can be represented a probability distribution, like decision making under risk.
According to Shannon :
“Simulation is the process of designing a model of a real system and conducting experiments with this model for the purpose of understanding the behavior (with the limits imposed by a criterion or set of criteria) for the operation of the system”.
According to Levin & Kirk Patrick :
“Simulation is an appropriate substitute for mathematical evaluation of a model in many situations. Although it too involves assumptions, they are manageable. The use of simulation enables us to provide insights into certain management problem where mathematical evaluation of a model is not possible.”
Contents :
- Meaning and Definition of Simulation.
- Scope of Simulation Techniques.
- Phases of Simulation.
- Application of Simulation.
- Types of Simulation.
- Models of Simulation.
- Benefits of Simulation.
- Limitations of Simulation.
- Monte Carlo Simulation Procedure.
- Random Digits and Methods of Generating Probability Distribution : Example.
Scope of Simulation Techniques :
Scope of Simulation in different area is as follows :
1) Healthcare (Clinical) Simulators :
Medical health simulators are developed and deployed to teach healing and diagnostic procedures. It is also used to teach medical concepts and decision making to personnel who are involved in the professions.
2) Computer Simulators :
Simulators have been proposed as an ideal tool for assessment of students for clinical skills. Programmed patients and simulated clinical situations, including mock disaster drills, have been used extensively for education and evaluation. These “lifelike” simulations are expensive, and lack reproducibility. A fully functional “3Pi” simulator would be the most specific tool available for teaching and measurement of clinical skills. Such a simulator meets the goals of an objective and standardized examination for clinical competence. This system is superior to examinations that use “standard patients because it permits the quantitative measurement or competence, as well as reproducing the same objective findings.
3) Military Simulations :
Military simulations are e models in which theories of warfare can be tested and advanced without the need for actual hostilities. It is also known as war games. They exist in different forms with various degree of realism.
4) Finance Simulations :
In financing computer simulation are often used for scenario planning.
5) Flight Simulators :
A flight simulator is used for the training of the pilots on the ground. A pilot gets permission by this technique to crash his simulated “aircraft” without being hurt. Pilots are trained with the use of flight simulators to operate aircraft in extremely dangerous situations, such as landing with no engines, or complete electrical or hydraulic failures. High-fidelity visual systems and hydraulic motion systems are included in most advanced simulators. The simulator is normally cheaper to operate than a real trainer aircraft.
6) Engineering, Technology or Process Simulation :
Simulation is an important feature in engineering systems or any system that involves many processes, For example, in electrical engineering, delay lines may be used to simulate propagation delay and phase shift caused by an actual transmission line. Similarly, dummy loads may be used to simulate impedance without simulating propagation, and is used in situations where propagation is unwanted. A simulator may imitate only a few of the operations and functions of the unit it simulates.
Phases of Simulation :
Step 1: Identify the Problem :
If an inventory system is being simulated, then the problem may concern the determination of the size of order (number of units to be ordered) when inventory level falls up to recorder level (point).
Step 2 : i) Identify the Decision Variables
ii) Decide the Performance Criterion (Objective) & Decision Rules
For example, demand (consumption rate), lead time and safety stock are identified as decision variables in inventory problem. These variables shall be liable to measure the performance of the system in terms of total inventory cost under the decision rule – when to order.
Step 3 : Construct a Numerical Model :
Construct a model which is possible to be analysed on the computer. Sometimes the model is written in a specific simulation language which is suitable for the given problem under analysis.
Step 4 : Validate the Model :
It is ensuring that the model should be representing the system truly which is analysed and the result will be reliable.
Step 5 : Design the Experiments :
Design the experiments with the, help of simulation model by listing particular values of variables to be tested (i.e. list of courses of action for testing) at each trial (run).
Step 6 : Run Simulation Model :
For obtaining the results in the form of operating characteristics run the model on the computer.
Step 7 : Examine the Results in Terms of Problem Solution :
Results are examined as well as their reliability and correctness. Best course of action is selected after completing the simulation process otherwise desired changes are done in model decision variables parameters or design, and return to step 3.