How_to_edit_user


			Multi_R_Designer Tutorial

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.

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.

`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 Exception`*must 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) };
     }
}

`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 = 15.1Math.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 automatically added.

See also Model applicability test

Model applicability test

When you perform a simulation, you can get information on the model's applicability for the results. The graphical representation of valid results are depicted by filled symbols. It can be done using two methods described below.

REMARK: This tutorial is the follow up of the How to add user model to Multi_R_Designer Section.
If you do not want to read this tutorial, you can download the solution and extract the files to TrickleBed/user/models.

Setting inputs/outputs applicability ranges in the model information dialog window

1. Edit model information (Applicability page)

Add the physical property Liquid superficial velocity in the Range panel and set the range from 1.4E-4 to 8.3E-4 m/s. When all required fields are defined, press OK.

The next time you start Multi_R_Designer, your model will be automatically updated.

Setting the model applicability specifications inside the code

In some models, applicability variables are used even if they are not part of the model inputs. In this case, you should use the following method to set the applicability range. The function void setValid(boolean bvalid) defined in the abstract class MRDModel is used to modify the internal applicability variable.

Use the function void setValid(boolean bvalid)only in the function public Number [] compute(Number inputs[]) throws Exceptionto set the applicability for each simulation.

import multirdesigner.model.*;
// This is not a true model
public class ValidSampleModel extends MRDModel
{
     public ValidSampleModel() {}
     public Number [] compute(Number inputs[]) throws Exception
     {
        // Inputs
        double L = inputs[0].doubleValue(); //Liquid mass flow rate
                   double d = inputs[0].doubleValue(); //Diameter
        double mul = inputs[0].doubleValue(); //Liquid viscosity
                // Reynolds number
                   double ReL = L * d / mul;
     setValid(ReL < 10); // Valid for Reynolds less than 10.
                 / Outputs
       double z = 2.4*Math.pow(ReL,-0.4); //X
        return new Double[] { new Double(z) };
     }
}

Multi_R_Designer Tutorial