User Model

Multi_R_Designer

How to add user model to Multi_R_Designer

This tutorial shows you the steps to follow to add a new model to Multi_R_Designer.

Requirements

1.The JavaTM 2 Platform, Standard Edition. You can download it from Sun Microsystem inc.

2. A text editor. On Windows platforms, you can use Notepad.

3. The models must be written in Java language. If your are not familiar with Java programming language, it is strongly recommended to read some of the Java Tutorial (at least Your First Cup of Java ).

Multi_R_Designer Model Architecture

When you start Multi_R_Designer, the software scans the directory TrickleBed/user/models to find the user's models.

A model is composed of three kinds of files :
1. A Model Information file (.info) : It contains the model name, inputs, outputs and much more informations (like validity range and comments).
2. A Java Source File (.java) : The source code of the model.
3. A Java Bytecode (.class) : The compiled version of the source code used by the software.

Your First Model

As an example, Ring and Missen have developed a model predicting Dynamic liquid holdup. (Ref: Can. J. Chem. Eng., vol 69, pp 1016-1020, 1991).
The correlation is defined by :

Where UL is the Liquid superficial velocity in SI unit (m/s).

1. Create a new model

Click on Create to begin the model creation.

2. Choose a Filename

Enter the model name. If you don't want to generate a Java Template File, deselect the box. However, this option simplify the creation of the model java source code.

3. Edit model information

Only the fields: Name, Input and Output are required.

Field What to do

Name Enter "Ring and Missen (1991)".

Input Click on the button "Add" and select Liquid superficial velocity in the list of properties.

Output Click on the button "Add" and select Dynamic liquid holdup in the list of properties.

When all required fields are defined, press OK. The model information is then saved in TrickleBed/user/models/Weekman.binfo.
If you have selected the template file option, a Java source file is created in the same directory in which you can write your code (your model).

4. Write your code for the model

Use the editor of your choice to edit the code.

An example of a template file generated by the Model Info Editor is shown below (Weekman.java).

import multirdesigner.model.*;
public class Ring extends MRDModel
{
public Ring() {}

public Number [] compute(Number inputs[]) throws Exception
{
   // Inputs
   double input0=inputs[0].doubleValue(); //Liquid superficial velocity rate

   // Enter your code here.

   // Outputs
   //double output0= ???? ; //Dynamic liquid holdup

   return new Number [] {new Double(output0)};
}
}

MRDModel is the abstract class used by the software as a valid model object. All models extend this class.

The function public Number [] compute(Number inputs[]) throws Exceptionmust be defined. This function is called by Multi_R_Designer for all simulations. All inputs and outputs units must be in the SI system.

Modification to do

a) Rename the variable input0 by ul
b) Rename the variable output0 by hd
c) Enter the correlation hd=15.51*Math.pow(G,0.679)
d) Save the file with the modifications

Solution (Ring.java)

import multirdesigner.model.*;
public class Ring extends MRDModel
{
     public Ring() {}

     public Number [] compute(Number inputs[]) throws Exception
     {
        // Inputs
        double ul = inputs[0].doubleValue(); //Liquid superficial velocity

                   // Outputs
       double hd = 15.1*Math.pow(ul,0.679); //Dynamic liquid holdup

        return new Double[] { new Double(hd) };
     }
}

5. Compile the source file

a) Open a command shell (Command Prompt on Windows).
b) Go to your user model directory (cd C:/Program Files/Multi_R_Designer/TrickleBed/user/models)
c) Verify that modellib.jar is in this directory
d) Type javac -classpath modellib.jar Ring.java

The next time you start Multi_R_Designer, your model will be automaticaly added.

Field	What to do
Name	Enter "Ring and Missen (1991)".
Input	Click on the button "Add" and select Liquid superficial velocity in the list of properties.
Output	Click on the button "Add" and select Dynamic liquid holdup in the list of properties.