Archive for September, 2011

NEW: PhytoSim Uncertainty Analysis

Thursday, September 15th, 2011

Ever wondered what the uncertainty of your model predictions is? Using the NEW PhytoSim Uncertainty Analysis module you will be able to find out just that.

An uncertainty analysis allows propagating parameter, initial condition and/or input uncertainties through the model to obtain the model output uncertainty. Setting up the analysis requires almost no work, just assign the source uncertainties, select the number of model evaluations and you are good to go. The well-known Monte Carlo technique is used to propagate the uncertainties and Latin Hypercube sampling is used to ensure that the uncertainty distributions are sampled evenly.

Screenshot of a source uncertainty while it’s being sampled:

PhytoSim Uncertainty Analysis source uncertainty distribution

Screenshot of the model output uncertainty (maximum, 95th percentile, mean, median, 5th percentile and minimum of the distribution):

PhytoSim Uncertainty Analysis model output uncertainty

For more information have a look at the PhytoSim Uncertainty Analysis User Guide webpage.

Pricing: Free for now (beta period will last until the end of 2011), afterwards 499 EUR.

Installation:

  • Make sure you have the latest PhytoSim version.
  • Select the Uncertainty Analysis module in the PhytoSim module manager and select ‘Install module’ from the toolbar.

 

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NEW: PhytoSim Sensitivity Analysis

Wednesday, September 14th, 2011

Probably the most important aspect of any modelling study is knowing which of your model parameters (and/or initial conditions) contribute most to the model output. As of today, such analysis is possible in PhytoSim.

The PhytoSim Sensitivity Analysis module offers 3 types of information:

Dynamic sensitivity functions: Shows how small changes in model parameters change the model output. By analyzing the sensitivity functions you will get a tremendous insight into your model.

PhytoSim Sensitivity Analysis Sensitivity Functions

Importance ranking: Ranks the model parameters according to their influence on the model output and shows this on a nice bar chart.

PhytoSim Sensitivity Analysis Ranking

Identifiability analysis: Use the intuitive user interface to find out which parameter combinations can be estimated based on a given set of measurements. You can even do the analysis before any real data is collected.

PhytoSim Sensitivity Analysis Identifiability

For more information have a look at the PhytoSim Sensitivity Analysis User Guide webpage.

Pricing: Free for now (beta period will last until the end of 2011), afterwards 499 EUR.

Installation:

  • Make sure you have the latest PhytoSim version.
  • Select the Sensitivity Analysis module in the PhytoSim module manager and select ‘Install module’ from the toolbar.

 

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PhytoSim v1.2 Released

Tuesday, September 13th, 2011

Version 1.2 of PhytoSim has been released. This release comes with updates for following modules: Data I/O, Modelling, Simulation and Calibration.

Download the Windows version here and the Mac version here.

For this occasion, all trial accounts have been reset enabling everyone to try out the new release.

Key new features:

  • Work offline on the Mac.
  • ‘Remember me’ option when logging in.
  • Data I/O:
    • Use date/time in outputs (converts from decimal time).
    • New output type: matrix file. Can contain matrix output from various PhytoSim modules.
  • Modelling:
    • New nounit( x ) function: returns the value of x without a unit, where x is a model component.
    • New pi() function: returns the number pi.
      WARNING: models having a ‘pi’ variable will now be invalid. Please replace these with ‘pi()’.
    • Multi-line comments. Use: ‘/*’ and ‘*/’ to enclose multiple lines of comments.
    • Added Collapse/Expand to the model navigator context menus to quickly expand/collapse the model tree.
    • New model: HydR, linking diameter changes to radial water transport across a radial hydraulic resistance (Steppe et al., 2011). Only available for non-trial accounts.
  • Simulation:
    • Added the ability to put all model component values to their defaults and/or initial values.
    • Added Collapse/Expand to the model navigator context menus to quickly expand/collapse the model tree.
  • Calibration:
    • Confidence information calculations: estimation errors and correlation matrix.
      PhytoSim Calibration Confidence Calculations
    • ‘Single shot’ optimizer: evaluate the objective at the initial values.
    • ‘Best’ simulation curve now has a +/- 2*stdev measurement uncertainty band on it.
    • Minimum and maximum graph marker lines for optimizer variables.

 

For a more detailed list of all new features, changes and bug fixes see:

 

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