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concepts:views [2009/11/05 21:17]
shona.weldon
concepts:views [2010/01/26 12:52] (current)
shona.weldon
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 Part of the design process is deciding what should be part of the rigid structure of the model and what should be dynamic and implemented by views. ​ Anything that needs to be flexible is usually implemented in views. Part of the design process is deciding what should be part of the rigid structure of the model and what should be dynamic and implemented by views. ​ Anything that needs to be flexible is usually implemented in views.
  
-==== Example 1: Extend a model by changing input data ====+==== Example 1: Extend a model by changing input data (create view) ====
  
 Suppose you had a model which had a control variable specifying exogenously the market share for new vehicles over time.  There are many ways to create that data and one must have been used to load the original model. ​ If you found a new algorithm for determining that market share based on something inside the model, something totally external or some mix of these, then a view could be written to implement this algorithm and feed it into the model as the new market share. ​ Essentially you have extended the model'​s scope but have taken on the work of actually modifying the model. ​ Of course the model can be changed later to encapsulate the new logic in the model itself but it doesn'​t need to. Suppose you had a model which had a control variable specifying exogenously the market share for new vehicles over time.  There are many ways to create that data and one must have been used to load the original model. ​ If you found a new algorithm for determining that market share based on something inside the model, something totally external or some mix of these, then a view could be written to implement this algorithm and feed it into the model as the new market share. ​ Essentially you have extended the model'​s scope but have taken on the work of actually modifying the model. ​ Of course the model can be changed later to encapsulate the new logic in the model itself but it doesn'​t need to.
  
  
-==== Example 2: Implementing feedback ====+==== Example 2: Implementing feedback ​(feedback view) ====
  
 Suppose you have a model with a coefficient in it which is NOT measured, for example an efficiency coefficient for a widget, and you need to estimate that coefficient. ​ In historic time you have a good estimate of the number of widgets and the amount of energy used by the widgets (observedEnergyUse). ​ You need to find an value for your coefficient that when multiplied by the number of widgets results in an energy use amount that tracks as close as possible to the observedEnergyUse. ​ A feed back view can be used to run the model check the difference in energy use, modify the coefficient appropriately,​ run the model again, and continue this loop until some acceptable level of convergence is achieved. Suppose you have a model with a coefficient in it which is NOT measured, for example an efficiency coefficient for a widget, and you need to estimate that coefficient. ​ In historic time you have a good estimate of the number of widgets and the amount of energy used by the widgets (observedEnergyUse). ​ You need to find an value for your coefficient that when multiplied by the number of widgets results in an energy use amount that tracks as close as possible to the observedEnergyUse. ​ A feed back view can be used to run the model check the difference in energy use, modify the coefficient appropriately,​ run the model again, and continue this loop until some acceptable level of convergence is achieved.
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 This is used extensively in the calibration process This is used extensively in the calibration process
  
-==== Example 3: Post Processing ====+==== Example 3: Post Processing ​(display view) ====
  
 Suppose you have an energy model that calculates fuel use and GHG emissions. ​ Then you get some coefficients for CAC emissions and you want to do a quick calculation to get the CAC emissions. ​ A display view can be written to take the results of the model and the new coefficients multiply them out and display the results. Suppose you have an energy model that calculates fuel use and GHG emissions. ​ Then you get some coefficients for CAC emissions and you want to do a quick calculation to get the CAC emissions. ​ A display view can be written to take the results of the model and the new coefficients multiply them out and display the results.
concepts/views.1257455829.txt.gz ยท Last modified: 2009/11/05 21:17 by shona.weldon