I am trying to calculate the uncertainty in the calculation of Local Sidereal Time using Pyephem, when I have many observation points with longitudes and timestamps with uncertainty.
What forumula does the observer.sidereal_time() use? Or in which .c file in libastro-3.7.5 is the LST calculation found?
Thanks
The sidereal_time() calculation calls now_lst() which you can find here:
https://github.com/brandon-rhodes/pyephem/blob/master/libastro-3.7.6/misc.c#L162
It only calls a few other functions, all of which should be described either directly in misc.c or in one of the nearby .c files there in the same directory.
Related
Im currently building a Anylogic model and want to calculate average time spent by customer in different flow paths (I have added the process flow below). In the picture i have named the paths i want to calculate the average time as path A and path B
Anyligic has dedicated blocks for this (although it can be done simply in code).
See in detail here.
The TimeMeasureEnd block contains a dataset.
The following code returns the average of the Y-axis values:
timeMeasureEnd.dataset.getYMean();
Good luck!
What I'm doing is a real-time application for visual servoing that needs to read an X and Y values of a coordinate during running time. As the simulation runs, these values are changed in time by a Python Script and then, I need to read every n milliseconds (say 20ms) this changing values in Simulink to move some DC motors based on the said (X,Y) coordinates.
To sum up, what I need is how to read in run-time values from an external file in Simulink. I could be a .txt, or any other kind of file but it has to read the changing values in real-time.
I'd totally appreciate your help!
I've tried to read a .txt file from a user-defined simulink block, but the functions I used are not supported in simulink, like fscanf.
I make a structure using Comsol then I want to make this structure subjected to a temperature variation ( T(begain)=25C then a temperature ramp (100 C/min) till T=250C and it lasts for 30 min then another temperature ramp (-100 C/min) till T=25C ).How could I make these temperature sweep?
You can define a function (e.g foo) that follows exactly your desired temperature with time profile. Then in the place where you specify your temperature (whether it is a boundary condition or domain condition) you insert foo(t), t being COMSOL's exclusive variable name for time.
You can do that for other variables too, space for instance. The easiest way to define foo is through the 1D interpolation option. Unfortunately, I do not currently have a COMSOL license to check it but I think you can simply enter the time and temperature values in the 1D interpolation table, choose a name and the interpolant style and just use it in the later part of the program.
I'am simulating magnetic fields in time domain with moving coils. Time dependent solver is needed for the movement and for temperature ramps as well. I think that you can use something like this, T=T_start+rate_of_change*t. The t variable is available with the time dependent solver and you can simply write the equation I mentioned. However, I think that you need to use time dependent solver three times, one for ramp up second for the constant temperature and third for the ramp down. Set the times for time dependent solvers so that you can made the desired temperatures.
First t=0s->(225/100*60)135s
second t=135s->(135+30*60)1935s
and last one t=1935s->(1935+135)2070s
You might also need to use compile solutions steps as well to add these three solutions together. I can try to do this tomorrow and check it.
Hope that this helped a bit
I am trying to make a fatigue analysis from a load series and I woudl like to extract the equivalent moment for
number cycles=1000000
years=25
I have a time series for one hour that looks like:
Then I have read that Rainflow Analysis is a very good tool to extract the cycles from a time history. Therefore I apply:
%Rainflow moment
dt=time(2)-time(1);
[timeSeriesSig, extt] = sig2ext(timeSeries, dt);
rf = rainflow(timeSeriesSig,extt);
I read that
OUTPUT
rf - rainflow cycles: matrix 3xn or 5xn dependend on input,
rf(1,:) Cycles amplitude,
rf(2,:) Cycles mean value,
rf(3,:) Number of cycles (0.5 or 1.0),
rf(4,:) Begining time (when input includes dt or extt data),
rf(5,:) Cycle period (when input includes dt or extt data),
If I am interested in the number of cycles what does the term rf(3,:) mean? It is only containing 0.5 and 1 in the vector. I want to obtain an histogram with the number of cycles per bin amplitude. Thanks
If you are using code from the File Exchange or another source, it helps to link to where you obtained it.
Here, rf(3,:) is showing you whether the amplitudes and other outputs refer to half or full cycles. The rainflow algorithm finds half-cycles first, and then matches tensile and compressive half-cycles of equal amplitude to find full cycles. There are normally some residual half-cycles.
If you examine the rfhist function contained within that same File Exchange submission, you will see how they handle full and half amplitudes. Basically, two half-cycles at any given load amplitude will be counted as one full cycle when creating the histogram.
G'day,
I have ocean model output in the form of netCDF files. The netCDF files are approximately 21GB, and the variables that I want to load are also pretty big (~ 120 * 31 * 300 * 400 sized matrices).
I want to load some of these variables from a netCDF file into MATLAB. Usually, I would do this via:
ncload('filename.nc',var1)
Which would load the variables var1 into similarly named MATLAB variables. However, since I only need a single column of var1, I only want to load a subset of var1 - This should speed up the loading process. For example, say,
size(var1)
>> var1 120x31x260x381
I only want the 31st column, and loading the other 30 columns, and discarding the information seems like a waste of time. In other words, this is what I want to accomplish: ncload('filename.nc',var1(:,31,:,:)).
I know there are a few different netCDF toolboxes floating around, and I have heard that one can use a stride flag to only load every xth entry... but I'm not sure if it's possible to do what I want. Does anyone know of a way to do this?
Cheers
If you have a current version of MATLAB, look for NCREAD and the example therein.