Modelling and simulation

NAT 

Egyszerűbb folyamatok modellezése Mérések és szimulációk, a paramétermódosítás hatásai, törvényszerűségek, modellalkotás egyszerű tevékenységekre

Why use computer models?

As well as financial modelling, spreadsheet software can be used for many other kinds of computer model:

• modelling supermarket queues
• modelling the stresses which will be borne by a new bridge
• modelling traffic flow in a new road system

Computer models are cheaper to setup than alternative methods that could be used to predict what will happen in a system, eg building a prototype. Other benefits include being able to:

• make alterations and quickly see the outcomes
• repeat tests several times over
• learn from "what if?" scenarios
• model dangerous situations safely

Limitations of computer models

A model is only as good as the rules used to create it. A mistake could have been made by whoever wrote the model and not every situation might have been considered - both of these issues could cause the model to give incorrect answers.

Computer simulation

 
A computer simulation is an application designed to imitate a real-life situation. A good example is software which simulates the experience of piloting a plane.

In the exam you may be asked to provide an example of simulation and list its advantages and disadvantages.

A real-life flight simulator - used for training pilots - is far more sophisticated, and is very expensive.
The pilot sits inside a specially designed cockpit on hydraulically controlled struts which move the cockpit to give the feel of the pitch and roll of a real plane. Sensors detect the actions of the pilot and move the cockpit accordingly. The view from the cockpit window is replaced with computer generated images.
Flight simulators give trainee pilots experience of:

• different flying conditions, eg poor weather, night flying
• emergency situations, eg frozen runways, fog, engine failure
• landing procedures and how they differ from airport to airport

Flight simulators are safe and cost effective too. No fuel is needed and there's no crew to pay, any damage to the plane is simulated, and the pilot is never at risk.

Other uses of simulation

• Nuclear power stations use simulation to improve output by looking at temperature, pressure and gas flow in the plant.
• Scientific experiments (for example plant growth) can be observed in varying conditions.
• Coastal erosion (the effect of the sea on the coastline) can be studied to anticipate possible flooding, so that defences can be best positioned.
• Traffic flow can be simulated in major cities to investigate the need for new roads and/or traffic lights.
• The aerodynamic effect on the shape of cars can be investigated by simulating air flow over different body shapes.

Virtual Reality

Head-mounted VR display

Virtual Reality (VR) is a computer simulation which allows the user to interact with the system. Special interfaces give the user the feel, sound and view of the virtual system. The user wears a head-mounted display through which the virtual world can be seen.

Advantages and disadvantages of simulation

Advantages

• It can avoid danger and loss of life.
• Conditions can be varied and outcomes investigated.
• Critical situations can be investigated without risk.
• It is cost effective.
• Simulations can be speed up so behaviour can be studied easily over a long period of time.
• Simulations can be slowed down to study behaviour more closely.

Disadvantages

• It can be expensive to measure how one thing affects another, to take the initial measurements, to create the model itself (such as aerodynamic wind tunnels).
• To simulate something a thorough understanding is needed and an awareness of all the factors involved, without this a simulation cannot be created.

 http://www.bbc.co.uk/schools/gcsebitesize/ict/modelling/1computersimulation_act.shtml

Source: http://www.bbc.co.uk/schools/gcsebitesize/ict/modelling

Algodoo science simulations

 http://www.algodoo.com

Frictional force
 air friction
 
Spring experiments
 spring constant
damping

Machines
 Windmill

Gravity
strength of gravity

Light
Refraction
Eye and glasses
Dispersion

Density
floating
sink