OxygenSensor.cpp

00001 #include "OxygenSensor.h"
00002 #include <cmath>
00003 
00004 static const float DEG2RAD = 3.141592654 / 180.;
00005 
00006 /**
00007  * constructs an OxygenSensor object.
00008  */
00009 OxygenSensor::OxygenSensor(const float temp0,
00010                const float temp100,
00011                const float phase0,
00012                const float phase100,
00013                const float pressure,
00014                const float salinity)
00015   : m_temp0(temp0), m_temp100(temp100), m_phase0(phase0),
00016     m_phase100(phase100), m_pressure(pressure), m_salinity(salinity) {
00017 }
00018 
00019 /**
00020  * calculates the percent of oxygen air saturation.
00021  *
00022  * @param temp  temperature, in degrees Celsius.
00023  * @param phase measured phase angle.
00024  * @return      percentage of air saturated with oxygen.
00025  */
00026 float
00027 OxygenSensor::calculate(const float temp, const float phase) const {
00028   const float f1 = 0.808;
00029   const float delphik = -0.0803;
00030   const float delksvk = 0.000433;
00031   const float m = 29.87;
00032 
00033   const float tanphi0_100 = std::tan((m_phase0 + delphik*(m_temp100 - m_temp0))
00034                 * DEG2RAD);
00035   const float tanphi0_m   = std::tan((m_phase0 + delphik*(   temp   - m_temp0))
00036                 * DEG2RAD);
00037   const float tanphi100_100 = std::tan(m_phase100 * DEG2RAD);
00038   const float tanphim_m     = std::tan(  phase    * DEG2RAD);
00039 
00040   const float A = tanphi100_100 / tanphi0_100 / m * 100*100;
00041   const float B = (tanphi100_100 / tanphi0_100
00042            + tanphi100_100 / tanphi0_100 / m
00043            - f1 / m - 1 + f1) * 100;
00044   const float C = tanphi100_100 / tanphi0_100 - 1;
00045 
00046   const float ksv100 = (-B + std::sqrt(B*B - 4*A*C)) / (2 * A);
00047   const float ksvm = ksv100 + delksvk*(temp - m_temp100);
00048 
00049   const float a = tanphim_m / tanphi0_m / m * ksvm * ksvm;
00050   const float b = (tanphim_m / tanphi0_m
00051            + tanphim_m / tanphi0_m / m 
00052            - f1 / m - 1 + f1) * ksvm;
00053   const float c = tanphim_m / tanphi0_m - 1;
00054 
00055   //  const float chlorinity = (m_salinity - 0.03) / 1.805;
00056 
00057   const float airsat = (-b + std::sqrt(b*b - 4*a*c)) / (2 * a);
00058 
00059   return airsat;
00060 }