Dew simulation

OPUR

Experimental data processing

Data fitting by least squares method

The purpose of the fitting is to obtain the values of the adjustment parameters T₀ , k and g (see our article). For the given T₀, a set of the optimal values for k and g is recorded for each day in the file k&g.txt, which is the main result of the data fitting procedure.
To perform this data processing sequence, one needs the data files of homogeneous format. This concerns both the file name and its contents. The file format conventions (except for YYMMDDvi.txt) are very strict. We give examples for each file format that we use. All data files are ASCII (text) files. All of them are organized into tab-separated columns.

Four data files are needed as input:

YYMMDDvi.txt in which all the data (except for the cloud cover) are present. Its format is not very strict. It is important that the 3^rd column is time in d:hh:mm:ss format and 5^th column is water mass in grams. This file is produced by TESTO apparatus.
D_YYMMDDvi.txt is created using YYMMDDvi.txt. See below for more details on its format. The cloud cover column should be created in it but its values are arbitrary. They will be substituted by the real ones later on.
n.txt in which the cloud cover data are present. It is supplied by the meteorological station and gives the cloud cover of the sky in octets (1/8 parts) each 3 hours. The format of each line is:
<station #>, AAAAMMJJHH,< cloud cover>
2.txt – the input data "File for Unit 2". for Condenser7.2.exe. It contains mainly the condenser parameters. This file need not to be modified by a text editor. It is modified by Condenser7.2.exe and can be saved under any desired name (we require the name 3.txt for processing purposes) as "File for Unit 3".

To start the processing, one needs to download seven executables available for Windows 98/NT4/2000/XP:

nebulo.exe – inserts the cloud cover data into D_YYMMDDvi.txt. You need to download the file setup_nebulo.exe into some temporary directory, run setup_nebulo.exe to unzip and run the Setup.exe. The Install Wizard will let you to install nebulo.exe. It can be moved after installation into any directory. The file setup_nebulo.exe and the files created during its unzipping can be removed after the installation.
Mv_File.exe – creates a directory structure and sorts the files. Requires list.txt as input
Condenser7.2.exe – the main condenser temperature fitting application. The purpose of this program is to find the k value (see our article) that provides the smallest variance Dev between the calculated (Tc) and measured condenser temperatures. There are two input text files: "File for Unit 1" and "File for Unit 2".
"File for Unit 1" contains 6 columns of the data separated by tabulation with a header line: time, u – wind velocity in m/s, N – cloud cover in octets, Ta – ambient temperature in °C, H – humidity in %, Tref – measured condenser temperature. The first 4 characters of this file must be "time". The first column gives time in seconds, such as 1:00:00:01 corresponds to 1x24x3600+1=86401.
    Once the files for units 1 and 2 are chosen, the "Input parameters" dialog window opens. It permits to adjust the parameters of the condenser, the initial and ending times of the simulation, the initial temperature, the value of g (to be guessed on this stage), the dew temperature correction T₀ (see our article), and the degree of smoothing of the experimental data on wind velocity, cloud cover ("nebulocity"), ambient temperature, and humidity. The actual beginning and ending times of the simulation correspond to the times from "File for Unit 1". Approximate values for them in decimal hours can be typed. These values will be rounded to the closest times from "File for Unit 1". The ending time (if after midnight) should be typed as <hour+24> to account for the day change. It is advised to choose both these times between the sunset and the sunrise because the program does not take into account the solar heating. The unused data (before the beginning time and after the ending time) is not included in the output "File for Unit 4".
    If one types "Auto" in the "Initial condenser temperature" box, the program chooses for the initial temperature the value of Tref corresponding to the beginning time. Any other number can be chosen either. The STOP button stops the execution of the program, CANCEL button cancels the changes in the window "Input parameters" by restoring the parameters from "File for Unit 2". After pressing OK button, the parameters are recorded in "File for Unit 3" (of the same format as "File for Unit 2"), to be chosen. The fitted and smoothed data are saved in "File for Unit 4", to be chosen either. The optimal value for k is recorded in the header of "File for Unit 4".
    The results of the temperature fitting are displayed then on the screen and can be either saved as the bitmap image or printed. The variance of (Tref – Tc) is displayed as Dev.
Modif_File.exe modifies the format of 3.txt ("File for Unit 2" for Condenser7.2.exe) and saves it as 3_11.txt ("File for Unit 2" for Condens11.exe). Requires list.txt as input.
Assm_File.exe See the description below.
Condens11.exe works similarly to Condenser7.2.exe. Its purpose is to find the optimal g value (see our article) that provides the smallest variance Dev between the calculated (m) and measured condensed masses of water. By default, it looks for M_YYMMDDvi.txt as "File for Unit 1" (where YYMMDD is the name for the current directory), from which the value of k is read. 3_11.txt is read as "File for Unit 2". It is overwritten as "File for Unit 3". "File for Unit 4 " is saved under the name FM_YYMMDDvi.txt. Time in the "File for Unit 4" is formatted as d:hh:mm:ss.
Extract kg.exe Extracts the values of k and g from the headers of all FM_YYMMDDvi.txt and saves them in k&g.txt. Requires list.txt as input.

Algorithm of the data fitting:

Put all files D_YYMMDDvi.txt into the same working directory <workdir>.
Run in the MS-DOS window commands
cd <workdir>
dir >> list.txt
The file list.txt is created. It contains the names of all the files as well as plenty of other information. Edit it by using the column block function (Alt+left mouse) of MS Word in order to clean up all other information and leave only the names of files which you put into <workdir>. Arrange these names into one column. Desired result
Move n.txt and nebulo.exe into <workdir>. Edit list.txt using the Replace (Ctrl+H) function of MS Word, replacing (Replace All) ^p by ^pnebulo .
NB: Type a space after "nebulo"! Edit the result and save it in n.bat. Run n.bat in the MS-DOS window. Check the date corresponding to each data file, confirm it by pressing <Enter>. The linearly interpolated cloud cover data is inserted into files D_YYMMDDvi.txt instead of zeros. The resulting file is saved as DN_YYMMDD.txt for each date. Instead of creating n.bat, you can run nebulo.exe many times opening one of your D_YYMMDDvi.txt files at a time.
Edit the file list.txt using the column block function (Alt+left mouse) of MS Word to delete the columns with D_ and vi.txt. Desired result.
Move Mv_File.exe into <workdir>. Run it. The directory structure is created. Each newly formed directory <datedir> has a name YYMMDD. The files D_YYMMDDvi.txt and DN_YYMMDD.txt are moved into corresponding <datedir>.
Move both Condenser7.2.exe and 2.txt into <workdir>. Find the optimal k value for each date from list.txt by fitting the condenser temperatures: run Condenser7.2.exe. Use DN_YYMMDD.txt as "File for Unit 1" and 2.txt as "File for Unit 2". Save "File for Unit 3" and "File for Unit 4" under the names 3.txt and FN_YYMMDD.txt in the corresponding <datedir>.
Move Modif_File.exe into <workdir>. Run it. It will create 3_11.txt for each date.
By now, each <datedir> should contain 3.txt, 3_11.txt, D_YYMMDDvi.txt, DN_YYMMDD.txt, and FN_YYMMDD.txt. Create the directory <workdir>\Testo. Move all the Testo data files YYMMDDvi.txt into it. Move Assm_File.exe into <workdir>. Run it.
Assm_File.exe moves each YYMMDDvi.txt from <workdir>\Testo to <datedir>. Then it takes the measured water mass data from YYMMDDvi.txt, the k value from FN_YYMMDD.txt and inserts them into DN_YYMMDD.txt. The result is saved as M_YYMMDDvi.txt in <datedir>. Assm_File.exe requires list.txt as input.
Find the optimal g value for each date by fitting the condensed water mass: move Condens11.exe into a <datedir>, run it; move it to the next <datedir>, etc. The files FM_YYMMDDvi.txt are created for each date. They contain all results of the fits: the measured and simulated time evolution of the water mass and condenser temperature calculated for the optimal values of k and g. These optimal values of k and g are recorded in the header.
Move Extract kg.exe into <workdir>. Run it. It will create k&g.txt that will contain the values of k and g for each date.

Author: Vadim S. Nikolayev