diff options
Diffstat (limited to 'deco.c')
| -rw-r--r-- | deco.c | 24 |
1 files changed, 22 insertions, 2 deletions
@@ -91,6 +91,7 @@ const double buehlmann_He_factor_expositon_one_second[] = { #define WV_PRESSURE 0.0627 // water vapor pressure in bar #define DECO_STOPS_MULTIPLIER_MM 3000.0 +#define NITROGEN_FRACTION 0.79 double tissue_n2_sat[16]; double tissue_he_sat[16]; @@ -215,6 +216,22 @@ double he_factor(int period_in_seconds, int ci) return cache[ci].last_factor; } +double calc_surface_phase(double surface_pressure, double he_pressure, double n2_pressure, double he_time_constant, double n2_time_constant) +{ + double inspired_n2 = (surface_pressure - WV_PRESSURE) * NITROGEN_FRACTION; + + if (n2_pressure > inspired_n2) + return (he_pressure / he_time_constant + (n2_pressure - inspired_n2) / n2_time_constant) / (he_pressure + n2_pressure - inspired_n2); + + if (he_pressure + n2_pressure >= inspired_n2){ + double gradient_decay_time = 1.0 / (n2_time_constant - he_time_constant) * log ((inspired_n2 - n2_pressure) / he_pressure); + double gradients_integral = he_pressure / he_time_constant * (1.0 - exp(-he_time_constant * gradient_decay_time)) + (n2_pressure - inspired_n2) / n2_time_constant * (1.0 - exp(-n2_time_constant * gradient_decay_time)); + return gradients_integral / (he_pressure + n2_pressure - inspired_n2); + } + + return 0; +} + bool is_vpmb_ok(double pressure) { int ci; @@ -243,15 +260,18 @@ void vpmb_start_gradient() } } -void vpmb_next_gradient(double deco_time) +void vpmb_next_gradient(double deco_time, double surface_pressure) { int ci; double gradient_n2, gradient_he; double n2_b, n2_c; double he_b, he_c; - double desat_time = deco_time / 60.0; + double desat_time; + deco_time /= 60.0; for (ci = 0; ci < 16; ++ci) { + desat_time = deco_time + calc_surface_phase(surface_pressure, tissue_he_sat[ci], tissue_n2_sat[ci], log(2.0) / buehlmann_He_t_halflife[ci], log(2.0) / buehlmann_N2_t_halflife[ci]); + n2_b = initial_n2_gradient[ci] + (vpmb_config.crit_volume_lambda * vpmb_config.surface_tension_gamma) / (vpmb_config.skin_compression_gammaC * desat_time); he_b = initial_he_gradient[ci] + (vpmb_config.crit_volume_lambda * vpmb_config.surface_tension_gamma) / (vpmb_config.skin_compression_gammaC * desat_time); |