MERLIN-Expo

The Model screen displays the mathematical model for the study and is in a sense the heart of the MERLIN-Expo software. It allows you to review all equations, parameters and variables of the model and to see how different parts of the model are related.

This screen also lets you modify the model by replacing parts or adding new parts from the library. This way the mathematical model can be customized to fit your study.

Two views are used to visualize the model, and you can switch between these using the Matrix and Graph buttons. The matrix arranges the sub-systems in the diagonal of a matrix with interactions displayed counter clock-wise in the off-diagonal elements. The graph shows the sub-systems as boxes connected with arrows.

The Information button opens a browser in which information on the currently selected blocks is presented.

The classic way of visualizing models is by using boxes and arrows; a graph. The graph is displayed by clicking the Graph button.

Use the left mouse button to select a sub-system or an interaction (arrow). To select multiple sub-systems, keep the CTRL key pressed while clicking the sub-systems. When a sub-system is selected, information about it is presented in the information panel.

You can move sub-systems by keeping the left mouse button pressed and moving the mouse.

Sub-system boxes will feature a small + button in the upper left corner. Clicking the + button will expand the box and show the contents within it. Collapse it by clicking the - button.

To connect sub-systems, move the mouse cursor to the center of the first sub-system. A green outline is displayed. Press the left mouse button and move the mouse cursor to the center of the second model. An arrow will now connect the first sub-system with the second model.

Notes:

1. MERLIN-Expo will often connect sub-systems for you when you add them from the library. It is only in special situations that you need to create or edit the connections.
2. Some sub-systems cannot be connected, hence no green outline will appear.
3. To specify what is connected, you should edit the connection.
4. The connection is one way. You might want to add a connection back from the second sub-systems to the first.

All action in the graph is accessed from the menu, which is displayed by clicking the right mouse button.

	Edit	Edit the currently selected sub-system
	Add>	Quickly add a new sub-system to the model from the library.
	Get from library…	Add a new sub-system to the model from the library window.
	Sub-system	Creates a sub-system; a box with the only purpose of grouping sub-systems, much like a folder in a file system. If sub-system are selected when this button is pressed, they will all be moved to the new sub-system.
	Group	Creates a group.
	Set background	Allows you to set the background for the model
	Toggle grid	Displays or hides a grid which simplify aligning sub-systems. When a sub-system is moved it will snap to the grid.
	Print…	Print the graph
	Zoom >
	Zoom In	Increase the size of the graph
	Zoom Out	Decrease the size of the graph
	Restore Zoom	Restore the zoom to the original 100%
	Layout >
	Tree	Organise the sub-systems as a tree
	Organic	Organise the sub-systems organically (with the most relevant sub-systems in the center)
	Hierarchical	Organise the sub-systems in a hierarchy
	Stack	Organise the sub-systems in a (vertical) stack
	Navigate >
	Enter	Display the currently selected sub-system
	Exit	Display the parent sub-system
	Home	Display the top sub-system

Interaction matrics are useful for models with many interactions. sub-systems are arranged diagonally, with interactions in the off-diagonal cells. This arrangement guarantees that off-diagonal cells never overlap and is great for smaller models with many interactions. However, for models with many sub-systems but few interactions, the matrix tend to become very big and somewhat clumsy to work with. The interaction matrix is displayed by clicking the Matrix button.

Use the left mouse button to select a sub-system or an interaction. When more than four interactions are displayed in the same cell, click the button to show all the interactions. To select multiple sub-systems, keep the CTRL key pressed while clicking the sub-systems.

You can move sub-systems by keeping the left mouse button pressed and moving the mouse. Press the button to open a sub-system and to close it.

To connect models, move the mouse cursor to the same row as the first model and to the same column as the second model. Right-click an select Connector from the menu.

Notes:

1. MERLIN-Expo will often connect sub-systems for you when you add them from the library. It is only in special situations that you need to create or edit the connections.
2. To specify what is connected, you should edit the connection.
3. The connection is one way. You might want to add a connection back from the second model to the first.

The menu of the interaction matrix will vary depending on the context (or location) in which it is presented. For instance, if you click an off-diagonal cell then buttons related to the diagonal cells only will be hidden.

	Edit…	Edit the currently selected sub-system or interaction
	Connector (off-diagonal)	If an off-diagonal cell is selected, and the source and target models can be connected, creates a connector from the first to the second model.
	Sub-system (diagonal cells)	Creates a sub-system. If sub-systems are selected when this button is pressed, they will all be moved to the new sub-system.
	Group (diagonal cells)	Creates a group.
	Add> (diagonal cells)	Quickly add a new sub-system to the model from the library.
	Get from library… (diagonal cells)	Add a new sub-system to the model from the library window.
	Insert above (diagonal cells)	Adds an empty cell above the currently selected cell (or to the top if no cell is selected)
	Insert below (diagonal cells)	Adds an empty cell below the currently selected cell (or to the bottom if no cell is selected)
	Delete	Removes the currently selected sub-system or interaction
	Zoom In	Increase the size of the matrix
	Zoom Out	Decrease the size of the matrix
	Restore Zoom	Restore the zoom to the original 100%

The visual properties of a sub-system can be changed by right-clicking the object and choosing Edit from the menu. The window which appears has four tabs (sub-systems):

Name - Change the (short) name of the sub-system. This name lets you identify the object in the simulation results, and is also used to refer to the sub-system in equations.

• General
  • Display name - The label of the object.
  • Font - The font for the label
  • Color - The background color
  • Background color used - Whether the background color is used or not. It is usually unnecessary to display a background color if an image is used (see below).
  • Image - Select an image to be used as the background.
  • Image shown - Whether the image is shown or not.
• Matrix
  • Visible - Displayed on the interaction matrix
• Graph
  • Visible - Displayed on the graph
  • Shape - Draw a (geometric) shape for the object
  • Glass effect - Draw a graphic glass effect for the object
  • Background image - Select a background to be displayed behind the sub-systems of a sub-system
  • Background shown - - Whether the background image is used or not.

These two tabs lets you select which objects of a sub-system that should be possible to connect to other sub-systems. You make an object available by selecting it in the left-hand list and clicking the » arrow.

Once selected, you can specify if it should allow more than one connection to another output/input.

Notes:

• It is unwise to change the pre-defined inputs and/or outputs, as these are required for the tool to function normally.

An arrow which connects two sub-systems is called a connector. It allows one sub-system to provide another sub-system with input data. When you right-click the arrow and choose Edit, a window appears which allows you to specify what data should be given to the target sub-system.

The window contains a table with three columns. The center column lists all inputs in the target sub-system. These are the data that the target sub-system asks for. By clicking the cells in the first column, you can select what data (which output) from the source sub-system should be given to the target. In the picture you can see a connector between an atmosphere model sub-system and a fruit model sub-system. The fruit model needs data for dry deposition. When clicking in the cell next to Surface dry deposition… a menu appears which lists the data offered by the atmosphere model. Only data which is still accessible (some data can only be used by one sub-system) and which has the correct unit is displayed in the menu.

You can add new sub-systems from the library to your model in two ways, both accessed from the right-click menu of the graph or matrix.

• Get from library… - Select a model sub-system from the library window. This window lets you read the description of the model before you add it.
• Add > - If you already know which model you want to add, you can quickly add the model from this button. Moving the mouse cursor will produce a sub-menu from which you can select a model.

If there are already model sub-systems in the project when a model is added, the software will ask if you want to automatically connect the new model sub-system with the existing sub-systems.