ITGS Textbook: Chapter 8 (Models and Simulations) Summary/Review/Study Guide

Computer Models

  • Models
    • Simplified representations of real concepts and events used to aid understanding or make predictions about outcomes without actually testing them.
  • Computer model
    • Computer program that creates a simplified, mathematical representation of a real world process.
  • Involve vast numbers of highly complex calculations
  • Often run on supercomputers
  • Use variables and processes to create representation of real world
    • Because models are simplifications, not guaranteed accurate result
    • However, real life decisions are made from simulations, so it is important to be as accurate as possible

Usually used for

  • Testing that is difficult or impossible to observe (ex: climate change, nuclear reactions, etc.)
  • Expensive or dangerous to test by experimentation


Applications of models

City Transportation Models:

  • Model traffic levels at different times of day
  • Predict what will happen when changes are made in transportation infrastructure (make new road, building a new bypass road, etc.)
    • Predict human and traffic behavior

Structural Models

  • Predict strength of buildings and bridges in severe events (earthquake, storm etc.)
  • Require complex detail about construction of buildings, materials, environment

Drug Interaction Models

  • Improve understanding of bacteria and virus that cause disease
  • Effect of doses of medication
  • Able to test variety of patients

Car Crash Models

  • Observe effect of accidents on cars, passengers, and pedestrians
    • Replace physical crash test
    • Complex mathematical physics
    • Can be repeated and compared with real life tests
    • Allow many different crashes to be tested
    • Computer models allows a wider range of variables to be measured and analyzed (compared to real life tests)

Computational Fluid Dynamics (CFD)

  • Models flow of liquid and gases, commonly used to test aerodynamics
  • Aircraft designers use this to asses lift capabilities of aircraft while in design stage
  • Allows various designs to be tried before materials, money, and time have to be committed to build something
  • Safer and cheaper than real experimentation

Climate Models

  • Model earth climate (predict weather) and scientific research (future climate change)
  • Used to make decisions which might affect millions of people and cost billions of dollars, so it is important that they are as accurate as possible
  • Hugely complex creation that tests the limits of our scientific knowledge and computing power.

Business and Finance

  • Decision Support Systems
    • Answer questions about possible future performance and assist in decision making
    • Answers: “What if” style questions (ex: what if we could reduce the defect rate from 3% to 1%)
    • Historical business data (sales, profits etc) incorporated in the model)

Why use models?

  • Generate “what-if” scenarios and input variables can be quickly changed to see effects
  • Cheaper and require fewer materials resources than real life tests
  • Safer than real life testing (in some cases)
  • Practical than real life testing sometimes (ex: when changing road layouts)
  • The only option sometimes (ex: dangerous situations)
  • Can be repeated with exactly the same input data (rarely possible in real life)

Computer Simulation

Computer Simulator:

  • Provide user with experience of a real life situation by combining computer models of the world with realistic input and output devices and (relatively) realistic graphics
  • Let users experience a situation in real-time

Flight simulators

  • common example of computer simulations used to train pilots and military
    • Combine computer models of the physics of flight, aerodynamics, and the aircraft structure with a realistic three dimensional representation of the world.
    • Use input devices like joysticks, switches, and levers, as found in real aircraft
    • Full motion platforms, allows people to raise, lower, rotate, and tilt to provide feedback to the pilot’s inputs and aircraft’s situation.
    • Accurate recreation of aircraft for added realism
    • Easily be recreated and practiced many times without risk

Driving Simulators

  •  example to train learner drivers or experienced drivers
    • Hazards and obstacles can be added for realism
    • Racers use simulator to test and make changes to a car design or setup virtually before applying it in real life.

Advantages of Simulators

  • Unusual or rare events can be simulated
  • Practice in situations without fear of loss or damage to people and equipment
  • Specific environmental condition can be simulated (no need to wait for it naturally)
  • People are unaffected by dangerous weather or darkness (safer)
  • Even though expensive, it is cheaper in the long term cost savings

Disadvantages of Simulators

  • Cannot offer exact reproduction of real world (even though realistic, might not be that accurate in real life)
  • Simulators use computer models (computer models = simplification of the real world)
    • Errors in data or process used to create the model will result in output which is less accurate.
  • Unable to create the exact feeling and pressure of being in a real world situation
    • It is less stressful to use a flight simulator than flying a real plane in real life

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