DODECO: EXPERIMENTAL DECOMPRESSION PROGRAM

ABSTRACT
This section describes and presents a decompression program called DODeco. It contains serveral decompression algorithms. It is meant to be experimental, so do not apply to real diving or decompression situations. The software contains errors. The purpose is to get insight in implementation of decompression algorithms. It has been designed to be easily extended with more algorithms.

Program

Disclaimer

Before reading further: the program is for experimental and educational purposes.
Do not apply to real diving or decompression situations.

Ok, having said that, please procede.

Introduction

Why writing a new decompression program when there are plenty available on the internet? The reason I wrote DODeco was to get insight in how decompression algorithms work. Most programs on the internet do not deliver source code. DODeco does. Including the architectural design that is described on this page. I hope it may give the user insight and that it may be the basis for further development.

The program is published as open source software under GNU Public licence.

Initially, the VPMDECO Fortran code of Erik Baker (implementing the VPM algorithm of Yount, Baker and Maiken) was taken as point of starting. It was translated to the Object Oriented software format in Java. It was designed in such a way that easily other alorithms could be added. I added VPM-B of Erik Baker, in which Boyle law compensation has been added. Furthermore I implemented Buhlmann ZH16-L and the Buhlmann algorithm that has been made more conservative by Erik Baker by adding a gradient factor.

The User Interface is separated from the calculation functionality. Though the user interface can be used to enter and edit dives, surface intervals, etc. it lacks a proper error handling and checking. You can enter nonsence exposures.

Features

Algorithms

VPMDECO (Erik Baker)
VPM-B (Erik Baker)
Bühlmann ZH-L16 (A, B and C variant)
Bühlmann ZH-L16 with gradient factor (Erik Baker)
Experimental algorithm (TO DO)

Tissue model

16 Tissue compartments, Helium and Nitrogen gas loading, Respiratory coefficient.

Output

Textual decompression table
Textual decompression table as .txt file
Graphical comparison between algoritms (TO DO)

Exposures

Saturation at certain height
Acclimatisation at height
Dive
Surface interval

Length Units

Meter
Feet

Export

Exposures saved as XML file

Import

XML file
Erik Baker VPMDECO/VPM-B format(TO DO)

Testing

The program has been tested by providing a few exposure patterns to it and to other software and verify the results.

The software has NOT been tested in practice. Of course the VPM algorithms and Bühlmann algorithms have been tested, but not in the form of DODeco. Errors may be present in DODeco. So do not use DODeco for real diving situations.

Download

• DODeco 1.0 source code, Javadoc, binary, etc.
• DODeco 1.0 Binary (JAR file) Note: IE saves it as ZIP!!
• Test Dives
• Metric settings file
• Imperial settings file

A lot of TO DO's exist:

• Implement Experimental algorithm
• Implement import of Baker format
• Implement graphical comparison
• Add an 'Options' dialg. Now settings are hard coded
• Optimise

How to use

Starting

Download the binary (JAR file). To run it, you need Java 1.5.0 or higher. A Java Runtime Environment can be downloaded at Sun for free, for Windows or Linux.

The software can be started by:

java -jar DODeco1.0.jar

The MainFrame is shown, presenting an overview of the exposures. See Figure 1. By default, there is always a 'Saturation'.

Figure 1 MainFrame with an overview of the exposures

To get going real fast, just select from the menu: File -> Example Dive. This loads an example dive sequence (as shown in Figure 2).

Figure 2 MainFrame with an overview of the exposures

Select from the Algorithm menu the appropriate decompression algorithm (or just leave it). Press the Calculate button. This calculates the decompression profile (Figure 3).

Figure 3 The resulting decompression profile

Adding your own exposures

Adding an exposure

We assume you started the program (Figure 1). This leaves you in the MainFrame overview. This overview shows the exposures to which the diver is exposed. There are 4 types of exposures:

Saturation

The first exposure is always a saturation. The diver is saturated at a certain height above sealevel. Only one saturation is assumed, like stated, at the beginning of the list.

Acclimatisation

It is possible to let the diver travel to a height above sealevel and let him/her acclimatise there for a certain period. This is what the Acclimatisation is all about.

Dive

The main dish: exposure to several segments of hydrostatic pressure and the necessary decompression. More than one dive can be added, separated by Surface Interval.

Surface Interval

The period between the dives.

Press the Add button to add a new exposure. By default the selection bar is set to the end of the list, so the new exposure is added here. Prior to pressing add, you may move the selection line to the position where you want to add the exposure. Anyway, after pressing the 'Add' button, the Add Exposure Dialog opens.

Figure 4 Add Exposure Dialog

Select the appropriate exposure you like to add. When pressing OK, the edit box is opened that allows you to fill in the details for the exposure you chose.

An existing exposure can be edited by selecting it and pressing the Edit button. An exposure can be deleted (except from the 1st) by selecting it and pressing the Delete button.

Edit Saturation

Figure 5 Edit Saturation Dialog

Edit Acclimatisation

Figure 6 Edit Acclimatisation Dialog

Editing a dive

When adding a dive (or pressing Edit to edit one), the Edit Dive Dialog opens. The Edit Dive Dialog (Figure 7) shows the components that make up a dive.

Figure 7 Dive Edit Dialog

There are three different components that make up a dive:

Ascent/Descent

This is a depth change. The change of depth takes place at a certain depth change rate. In the Edit Dive Dialog the Ascent/Descent is indicated by 'Asc/Desc' in the 1st column.

Stay

This is a period at which the diver stays at a certain depth. This is indicated in the Edit Dive Dialog by 'Stay' in the 1st column.

Deco stage

During the decompression stage, the diver decompresses to a shallower depth using a certain gas mixture. More stages can be added, when more gas mixtures are used. A Deco Stage is indicated by 'Deco' in the 1st column.

To add a new component to the list, select the position in the list where to add (leaving the default selection appends the component to the list) and press the Add button. This opens the Add Dive Component Dialog (Figure 8).

Figure 8 Add Dive Component Dialog

Select the appropriate Dive Component and press Ok button (the Cancel button closes the Dialog without an component to be added). After adding a Dive Component, the appropriate Edit Dialog for the Component opens up.

Edit Ascent/Descent

Figure 9 Edit Ascent/Descent Dialog

Edit Stay

Figure 10 Edit Stay Dialog

Edit Deco Stage

Figure 11 Edit Deco Stage Dialog

Edit Surface Interval

Figure 12 Edit Surface Interval Dialog

Settings

Settings are read from an XML file named settings.xml. Setting files are available in the download section for imperial and metric unit systems. If the settings file is not present in the current directory, hard coded settings are used.

Settings can be loaded from the menu, prior to creating dives or executing calculations. Use File -> Load Settings. You can also rename the downloaded or created settings files to settings.xml and place them in the start-up directory.

Software design

This section presents a description of the software. Diagrams are presented in UML (Unified Modeling Language). Basic knowledge on software development, software architecture and UML is prerequisite.

Packages

Figure 13 Packages

Following packages are present in the software:

net.deepocean.dodeco.calculator

This package contains the calculation classes and algorithms. Its responsibility is to represent the diver and diving situations and calculate the decompression profiles.

net.deepocean.dodeco.tools

This package contains some tools, like a class to read and write XML files.

net.deepocean.dodeco.ui

This package contains the user interface classes.

org.netbeans.lib.awtextra

This package contains a few classes that make absolute laying out possible within Java. This layout is used by the user interface.

The ui package has a dependency towards the calculator package. The dependency is not vice versa. This enables adding other user interfaces, without modifying the calculator package.

The net.deepocean.dodeco.calculator package

This package is the heart of the software. It offers representation for the Diver and the diving situations. It contains a number of Decompression algorithms.

Figure 14 Concept of net.deepocean.dodeco.calculator

The base structure is presented in Figure 14. The Processor class is the entry point. It contains a Diver instance and (a Vector of) Exposures. When executing, the Exposures are applied to the Diver, updating the Divers TissueCompartments.

Figure 15 Exposures

Figure 16 The Dive class

Figure 17 The ExposureSegment tree