def convert(x, name):
"""Try to convert string to a Python object.
if not possible return a string
name: if "date time", force conversion from string to seconds"""
if name == "date time": return timestamp(x)
try:
return float(x)
except:
pass
try:
return timestamp(x)
except:
pass
return x
def update_data():
from time_string import timestamp
status = "Merging..."
t = nom_delay = act_delay = zeros(0)
for logfile in logfiles.values():
t = concatenate((t,[timestamp(d,"") for d in logfile.date_time]))
nom_delay = concatenate((nom_delay,map(filename_delay,logfile["filename"])))
act_delay = concatenate((act_delay,logfile.act_delay))
data.t,data.act_delay,data.nom_delay = t,act_delay,nom_delay
def start_time(self):
from time_string import timestamp
from time import time
lines = self.lines((0, 80))
try:
t = timestamp(lines[0][0])
except:
t = time()
return t
def next_timestamp(text, offset):
from time_string import timestamp
from numpy import nan
i = text.find("\n", offset) + 1
if i < 0: t = nan
else:
j = text.find("\t", i)
if j < 0: t = nan
else: t = timestamp(text[i:j])
return t
"//Femto/C/All Projects/APS/Experiments/2016.11/Logfiles/Sample-Temperature-1.log"
timezone = "-06" # CST
# Parameters
c = 15.0 # sample heat capacity [J/K]
Rin = 1.0 # thermal resistance heater-sample [K/W]
Rout = 10.0 # thermal resistance sample-ambient [K/W]
sigma1 = 0 #1e-8 # radiative coupling heater-sample [W/K^4]
sigma2 = 0 #1e-9 # radiative coupling sample-ambient [W/K^4]
Tout = 273 + 29 # ambient temperature
info("Loading data")
Tin_log = table(Tin_logfile, separator="\t")[53180:]
T_log = table(T_logfile, separator="\t")[:-120]
t_Tin = array([timestamp(t + timezone) for t in Tin_log.date_time])
T_Tin = Tin_log.value + 273
Tin = interp1d(t_Tin, T_Tin, kind='linear', bounds_error=False)
t = array([timestamp(t + timezone) for t in T_log.date_time])
T = T_log.value + 273
def dT_dt(T, t):
"""Derivative of temperature T at time t."""
Pin = 1. / Rin * (Tin(t) - T) + sigma1 * (Tin(t)**4 - T**4
) # heat float into sample
Pout = 1. / Rout * (T - Tout) + sigma2 * (T**4 - Tout**4
) # head flow out of sample
dT_dt = 1. / c * (Pin - Pout) # rate of temperature change
return dT_dt