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lib/Deco/Tissue.pm  view on Meta::CPAN

    $self->{previousdepth} = 0;

    # some timestamps in seconds
    $self->{time}->{current}  = 0;
    $self->{time}->{previous} = 0;
    $self->{time}->{lastdepthchange} = 0;

    # oxygen exposure tracking through OTU's
    $self->{otu}   = 0;

    # haldane formula for current parameters, returns a ref to a sub
    $self->{haldane} = $self->_haldanePressure();

    return $self;
}

# get the tissue nr
sub nr {
    my $self = shift;
    croak "Tissue numbers not set yet" unless ($self->{nr});
    return $self->{nr};

lib/Deco/Tissue.pm  view on Meta::CPAN

    croak "Depth can not be negative" unless($depth >= 0);

    if ($depth != $self->{depth} ) {
	$self->{previousdepth} = $self->{depth};
        $self->{depth}         = $depth;
	
	# remember this depthchange on the time scale
	$self->{time}->{lastdepthchange} = $self->{time}->{current};
	#print "Time of last depth change is: " . $self->{time}->{lastdepthchange} ."\n";

	# when depth changes we need to recalculate the Haldane formula
	$self->{haldane} = $self->_haldanePressure();
    }

    return $self->{depth};
}

# set new timestamp in seconds

sub time {
    my $self = shift;

lib/Deco/Tissue.pm  view on Meta::CPAN

# convert meters to bar
# this does NOT include the starting pressure
# so 0 meters = 0 bar water pressure
sub _depth2pressure {
    my $self = shift;
    my $depth = shift;
    my $press =  $depth  * $self->{waterfactor} / 10;
    return $press;
}

# use haldanian formula to solve the current pressure in tissue
# as long as the depth remains constant, this formula is still valid
sub _haldanePressure {
    my $self = shift;
    my $gas  = lc(shift) || 'n2';
    croak "Asking for unsupported gas $gas" unless exists $GASES{$gas};

    # we need the current tissure pressure, at t=0 for the depth
    my $tissue_press0 = $self->{$gas}->{pressure};
    #print "recalculating haldane formula. tissue pressure at t0 = $tissue_press0\n";

    # and the alveolar pressure
    my $alveolar = $self->_alveolarPressure( depth => $self->{depth} );

    # the time in minutes we have been at this depth, note that internal times are in seconds!
    return sub {
		my $t = shift;
		$alveolar + ($tissue_press0 - $alveolar ) * exp( -1 * $self->k() * $t );
    }