PHS.js is a JavaScript implementation of the Predicted Heat Strain (PHS) model described in the standard "ISO/FDIS 7933 Ergonomics of the thermal environment — Analytical determination and interpretation of heat stress using calculation of the predicted heat strain". PHS.js is based on "Predicted Heat Strain (PHS) model: computation program written in Quick Basic" in Annex E of the standard.
PHS.js export the following functions:
Loading PHS.js results in a global variable boj.PHS which contains an associative array with references to the exported functions.
Parmeters are handeled using parameter_util.js, which provide functions for setting default values and accessing the parmeters. In the beginning of PHS.js there are descriptions of the parameters. Parameters in par_spec_sim must not be changed during a simulation. Paramters in par_spec_step can be changed between time steps in the simulation.
The text below assumes the statetment var phs = boj.PHS;
.
The main steps in a PHS simulation are:
phs.reset();
phs.sim_init();
phs.time_step();
phs.current_result()
PHS_wci.js (used by PHS.html) is an example of how PHS.js can be used.
One of the goal with PHS.js is to be CPU efficient.
The time_step()
function will be the most frequently
used function and it should do as little as possible.
Calculations which results do not changed in a time step are done by the change of
parameters.