Filip Claeys

"No algebraic equations found. No sorting done." is not an error but rather a warning (it will appear in DESIGN mode when the so-called "dummy" executable model is built). It is of no importance and can be safely discarded.

I assume you are not using the latest version of WEST (i.e. 2017) since in this version loop breakers are inserted automatically. Also in WEST 2016 it is possible to have loop breakers inserted automatically, but this option is not switched on by default.

Yes, Step size determines the magnitude of the changes of the tuned parameters, so a Step size of 0 will lead to values that don't change at all.

Create a top-level parameter (cf. p 101 in the User Guide) for each parameter of interest, and then use those top-level parameters in your calibration exercise.

Which optimization solver algorithm are you using? Did you supply a Step size and Scaling factor (if Auto-scale is off) for each tuned parameter?

Please have a look at the Models Guide under Models / Flow / Flow Splitters & Models / Flow / Fraction Splitters.

Basically the difference is that for the flow spitter one specifies the absolute value Q_Out2 of the 2nd outgoing flow (the 1st is then Q_In - Q_Out2). For the fraction splitter one specifies the relative fraction of the incoming flow f_Out2 that is to be associated with the second outgoing flow (Q_Out2 = f_Out2 * Q_In). Flow splitters do not affect the concentrations.

> 1) Is it possible to change the selected biological model (Instance) once I've created the ptoject? How?

Yes, this can be done through the "Block Library Setup" dialog, which is in the "Project" menu (as of WEST 2014).

> 2) I've noticed that when you launch a DYN simulation it starts from the final values of the previous SS simulation.

The behavior can be altered by switching off the flag labeled "Automatically copy the current state of the Steady State simulation to the Dynamic simulation", and manipulating the "Initialize Simulation" options in the "Project" menu.

> Is it possible to repeat cyclically the influent pattern (without copying and pasteing it several times in the .txt input file)?

The WEST engine actually supports this, but this functionality is not available through the GUI.

> 3) It seems to me that you can load your input data from a .xls or .txt file but I have some problems in order to recognise the correct units when I use a .xls files (especially the time column). How can avoid that? or should I use always .txt files?

You should be able to use either TXT or XLS(X). In the case of TXT 2 header styles are supported, i.e. the old style with "%%Version3.3...", and the newer style with "#". In the case of XLS(X) only the latter is supported.

> 5) Is it possible to see the mathematical equation of each model and how are they implemented in west?

The Model Editor (only available with WESTforOPTIMIZATION) is the tool to use to explore and modify the model library's structure and equations.

1) Tick the "Interpolated" check button in the Simulation Properties / Output tab

2) No, it is not possible to use 2 Instances in the same Project. What is possible however is to create a new Instance in the Model Editor that is associated with multiple Categories (most likely this will require introducing transformer models and prefixes to resolve name clashes)

You have to open the Analysis Properties window by clicking the "Analysis" button in the "Project" menu. Under the "Variables" tab you have to remove all references to "out1", which no longer exists.

Yes, the default is 0.5d for both SS and DYN, which especially for the latter may not be appropriate and will have to be modified (either to another fixed interval, or to a number of equidistant points).

For future versions, we may change the defaults, and possibly make them different for SS and DYN.

The uninstall process modifies the registry, which requires certain privileges. Are you running the process as Administrator?