IB ITGS THEORY



IB ITGS THEORY

STRAND 3.8 SPREADSHEET, MODELING AND SIMULATION

B) MODELING AND SIMULATION (from kennedyb.co.nr section 2.2.5)

(i) MODELING

Definitions:

A computer model is a program which has been developed to copy the way a system in real life works

A model defines the relationship between two or more things.

It makes use of mathematical equations to define that relationship.

The main point of a model is to make predictions.

For example we can have a  model of predicting a persons’ likely weight in a year from now.

First of all decide what are the inputs to the model. In this case we consider two things – their current weight and the amount of excess calories they eat.

Set up a basic equation:

Predicted Weight = Current Weight + Factor x Excess Calories

The model looks very simple, but there are questions to be asked that make it more complicated – What is the value of the “Factor” in the model. Does it change with time, does it change with each person?

A model often has to use a number of equations in order to be realistic. The trickiest part of creating a model is working out what are the true relationships between its inputs and outputs.

In practise computer models can be produced using:

u     spreadsheets;

u     computer graphics, including charts;

u     simulation programs

u     virtual reality systems;

u     expert systems;

Types of modeling:

1. Computer Modelling

Computers are well suited for modelling as they can calculate equations extremely quickly. But even these machines struggle when things get really complicated such as running a weather prediction model. The most powerful computer on the planet is being used to run models of nuclear reactions. This avoids carrying out real nuclear explosions.

2. Spreadsheet Modelling

For everyday use, a spreadsheet is excellent for running a model. This enables businesses to test out scenarios. For example what would happen if my sales increased by 5% or what would happen if my profit margin reduced by 10%.

4. 3D Modelling

Designers can set up a 3D model of a single component or an entire car within the computer. A 3D Computer Aided Design (CAD) package is used to do this.

This allows the designer to try out many ideas before actually building an expensive prototype.

ITGS SL – Exercise 3.8.1 – Virtual Reality

1.   In your own words outline the similarities and differences between the following: (6marks)

• BOOM

• CAVE

• HMD

2.   Distinguish between immersive and non-imersive VR technologies. Provide examples. (3marks)

3.   Explain whether VRML is immersive or non-immersive VR technology. (3 marks)

4. Outline 4 areas of business that VR would be helpful. For each area describe how it might be applied. (8 marks)

You may need to do some additional research here, for examples, type the keywords ‘VR application’ or ‘virtual reality’ into a search engine.

Total -  /20 marks

5. Expert Systems

An expert system is a type of modelling. A expert system is a computer program which simulates the knowledge and experience of a human expert. An expert system tries to give advice based on a set of rules built into it and a set of inputs that you provide. There are medical expert systems that help doctors make diagnosis of what is wrong with a patient. The doctor provides details of their symptoms and the expert system suggests a number of things it could be.

Who uses Modelling ?

1. Scientists

Often use modeling to predict the outcome of an experiment. If the result of the experiment is the same as what their model predicts, then it proves their theory is accurate. This is how science works – develop a theory, make a prediction, prove it by experiment. Scientists try to predict dangerous events in order to allow us to make plans should the events happen. For example predicting the likely spread of a disease. In this case modelling is an excellent tool.

2. Economists

They are concerned with predicting the effect of changing something in the economy. For example if income tax went up, what effect would it have on the wealth of our nation? The Treasury runs a model of the UK economy to try and answer questions such as this. It is very complex with over 1,300 equations.

3. Climatologists

They are involved with predicting climate change. There are a number of huge models used to predict what effect various things such as burning coal will have on Global Warming.  The issue with these models is that they each produce a different result, so making it difficult to decide which is the ‘right’ one to use.

|ITGS SL Exercise 3.8.2 – Models |

| |

|1. Pilots training in Scotland for a commercial license are being given the opportunity to fly training flights to almost every airport in |

|Europe – without having to leave the ground. |

|(Story from BBC NEWS) |

| ) |

|Discuss the advantages and disadvantages of this training method, in 200 – 300 |

|words.                                                                    {10 marks} |

|2. Read the following article: Cosmic dust disc to force rethink – |

|(Story from BBC NEWS By Dr Chris Lintott  Co-presenter, BBC Sky At Night, Austin Monday, 14 January 2008, 14:51 GMT) |

|Explain the reliability of computer generated models. Backup your opinion using the article. {10marks} |

| |

|Total -  /20 marks |

(ii)SIMULATION

A computer simulation is a program which not only models the system but also uses equipment to provide a physical experience

A Simulation tries to copy or mimic something that can happen in our physical world. A simulation make use of a model. The model can be physical, mathematical or both.

[pic]_

|1. Physical (Hardware) Simulation | |

|The tank opposite is full of water with a coloured ball floating in it. | |

|It is trying to mimic the ocean and the effect it has on objects such as sea buoys which are used to measure weather in the deep oceans. | |

|This is a physical simulation as it behaves in the same way as the thing it is represents – except it is a lot more manageable than the ocean! | |

|2. Mathematical (Software) Simulation | |

|These are excellent for systems that are well understood i.e the equations work well. | |

Examples of simulations:

|1. Weather Simulation |

|Most of us want to know what the weather holds for us in the next few days. It is especially important to predict where a hugely |

|dangerous storm such as a hurricane is going to land. Everyone in its path needs a warning in order to prepare their houses and make |

|an escape. In this case a computer simulation of the hurricane is set up in order to predict its behaviour. |

|2. Car Crash Simulation |

|It is vital that cars and trucks are designed to be as safe as possible. Computer Simulations are created that can accurately predict |

|how the car will behave.  Engineers can then make adjustments to the car design to make it even better. This also saves time and |

|money, so it is worth the huge effort it takes to get the simulation working right. |

| |

| |

|3. Game Simulation |

|Many computer games are actually simulations as they try to mimic the physical world in some way. You play the game by changing the |

|inputs to the simulation / game. Examples: |

|Theme Park |

|The Sims |

|Railroad Tycoon |

|4. Flight Simulators and Training Simulators |

|It is often too dangerous to let untrained staff loose on a piece of equipment. For example how nervous would you be if you were on a |

|flight where the pilot had never flown the plane before? In order to prepare the pilot, flight simulators have been developed. They |

|are a mixture of physical and software simulations. The cabin looks and behaves exactly like the real thing, whilst the outside world |

|is simulated in software. |

Homework – Exercise 2.2.5.3 – Simulations

1. 1. Attempt ex 4.35 & 4.36 on page 186 from Gift of fire (You can read Gift of fire pg 171-186)

{10 MARKS}

1. 2. Read TOMMOROWS TECHNOLOGY AND YOU PAGE  168 and attempt review qs 14

{10 MARKS}

WORKSHEET MODELLING USING” WHAT-IF” ANALYSIS FEATURE

What-if analysis is a process of changing the values in cells to see how those changes affect the outcome of formulas on the worksheet. For example, varying the interest rate that is used in an amortization table to determine the amount of the payments. (From Microsoft Excel Help Facility)

WHAT-IF” ANALYSIS TOOLS:

1. SCENARIOS TOOL

(From Microsoft Excel Help Facility)

PRACTICAL EXERCISE A – HOME WORK – Do not submit, but very important for you

Start MS EXCEL application software. Then Click Scenarios on the Tools menu.

When the Scenario Manager dialog box opens, fill it up with relevant simulated data and see how excel Scenario manager works. USE MS Exel help facility if stuck.

2. GOAL SEEK TOOL

(From Microsoft Excel Help Facility)

PRACTICAL EXERCISE B – HOME WORK – Do not submit, but very important for you

Start MS EXCEL application software. Then Click Goal seek on the Tools menu.

When the Goal seek dialog box opens, fill it up with data in the box above and see how excel Goal seeking works. USE MS Exel help facility if stuck.

DIFFERENCE BETWEEN VERIFICATION & VALIDATION

In the modeling and simulation community, validation determines the degree of accuracy of associated data to the real world according to the model; verification determines whether a computer model and the associated content represent the developer’s conceptual descriptions and specifications.

From: (accessed Monday, March 21, 2011)

Validation is the checking of data before processing to ensure that it is acceptable for it or not. E.g. When entering a date, the validation for month is 1-12, you cannot enter 13, its out of range. Similarly a telephone number cannot contain letters.

Whereas Verification is the checking of data that has been copied from one place to another to ensure that is replaces the original one. E.g. PASSWORD. When you sign up in a site, just like WIKIANSWERS, you have to enter your password twice, the second entry being compared with the first.

From (accessed Monday, March 21, 2011)

In the modeling and simulation community, validation determines the degree of accuracy of associated data to the real world according to the model; verification determines whether a computer model and the associated content represent the developer’s conceptual descriptions and specifications.

From: (accessed Monday, March 21, 2011)

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