This document discusses a study conducted using Code_ASTER to analyze the dynamic behavior of a pump. 400 training simulations and 100 testing simulations were run on the Simulagora cloud computing platform. The simulations examined the effects of uncertain radii parameters on pump frequencies. The training simulations took 25 days to complete using distributed computing on Simulagora. Surrogate modeling methods were used to build models from the training data to predict frequencies for the testing data points. Lessons learned from using Simulagora included fixing bugs and improving the Python API based on feedback.

1. Collaboration:Aster Pronet – March 27, 2015
Study of the dynamic behavior of a pump with
Code_ASTER on Simulagora
Collaboration:
Florent Cayré
Karina Macocco
Felipe Aguirre
Aster Pronet
March 27, 2015

2. Collaboration:Aster Pronet – March 27, 2015
… solutions for robust engineering
SICODYN Benchmark
Surrogate modeling

3. Collaboration:Aster Pronet – March 27, 2015
SICODYN Benchmark
Study of the pump casing – variables & definition domain
Uncertain parameters are the radius of the connecting screws of the frame with the other
elements.
Uniform distributions
Radius type 1 [m] : [0,0088 ; 0,0132]
Radius type 2 [m] : [0,011088 ; 0,016632]
Radius type 3 [m] : [0,011088 ; 0,016632]
● 400 training points and 100 testing points
● 1h30 minutes per simulation with high RAM consumption (10 GB).
●
Total simulation time :
– 25 days for the training points (Distributed with Simulagora)
– 6,25 for the testing points (Distributed at Phimeca over 3 cores)
©PhimecaEngineeringLibreRestreintPhimecaConfidentiel

4. Collaboration:Aster Pronet – March 27, 2015
Input of the design of experiment
Sobol Sequence
• 400 points for the training
dataset.
LHS
• 100 points for the testing
dataset. Highlighted in the
graph.
©PhimecaEngineeringLibreRestreintPhimecaConfidentiel

5. Collaboration:Aster Pronet – March 27, 2015
Output of the design of experiment
Frequencies
©PhimecaEngineeringLibreRestreintPhimecaConfidentiel

6. Collaboration:Aster Pronet – March 27, 2015
MAC matrix of the VGP
©PhimecaEngineeringLibreRestreintPhimecaConfidentiel

7. Collaboration:Aster Pronet – March 27, 2015
Adjustment graph of the VGP
©PhimecaEngineeringLibreRestreintPhimecaConfidentiel

8. Collaboration:Aster Pronet – March 27, 2015
Validation of the VGP
©PhimecaEngineeringLibreRestreintPhimecaConfidentiel

9. Collaboration:Aster Pronet – March 27, 2015
Validation of the VGP
©PhimecaEngineeringLibreRestreintPhimecaConfidentiel

10. Collaboration:Aster Pronet – March 27, 2015
Simulagora in few words...
Public cloud based
– Computation and storage
resources
– Enormous power
– Super-fast computation resources
ramp-up
Server
Cloud
Simulagora
Cloud
Simulagora
Browser
WWW
A platform using Web
technology to ease grid
computation by leveraging
cloud resources
HPC in the cloud

11. Collaboration:Aster Pronet – March 27, 2015
Implementation on Simulagora
Modeling
Results
analysis
● Modeling and results analysis performed on Phimeca infrastructure
● Could have been done on Simulagora too
Single computation
setup
Complete study setup
and monitoring
Simulagora

12. Collaboration:Aster Pronet – March 27, 2015
Simulagora - single computation setup
● Transfer input data : using the Web interface
Technicalities
● Data integrity check
● Resume on failure

13. Collaboration:Aster Pronet – March 27, 2015
Simulagora - single computation setup
● Transfer input data : using the Web interface
Technicalities
● Data integrity check
● Resume on failure
No install
No setup

14. Collaboration:Aster Pronet – March 27, 2015
● Transfer input data : using the Python API
– Simple config file
– Simple Python script
Technicalities
● Open Source
● Easy install, easy setup
● Web services (no firewall pb)
Simulagora - single computation setup

15. Collaboration:Aster Pronet – March 27, 2015
● Transfer input data : using the Python API
– Simple config file
– Simple Python script
Technicalities
● Open Source
● Easy install, easy setup
● Web services (no firewall pb)
Simulagora - single computation setup
Fast install
Easy setup

16. Collaboration:Aster Pronet – March 27, 2015
● Launch an interactive session
Simulagora - single computation setup
Technicalities
● Full root access
● Max session time
● File modifications saved

17. Collaboration:Aster Pronet – March 27, 2015
Simulagora - single computation setup
Technicalities
● Requires a high-bandwidth
connection
● Full-featured lightweight
window manager
● Connect to your machine in your browser

18. Collaboration:Aster Pronet – March 27, 2015
Simulagora - single computation setup
No install
No setup
Technicalities
● Requires a high-bandwidth
connection
● Full-featured lightweight
window manager
● Connect to your machine in your browser

19. Collaboration:Aster Pronet – March 27, 2015
Simulagora - single computation setup
● Connect to your machine in text-mode
Technicalities
● Uses the SSH protocol
(rarely blocked by firewalls)
● Fast even with low-
bandwidth connections
● Requires a simple setup
(a bit more on Windows)

20. Collaboration:Aster Pronet – March 27, 2015
Simulagora - single computation setup
● Connect to your machine in text-mode
Technicalities
● Uses the SSH protocol
(rarely blocked by firewalls)
● Fast even with low-
bandwidth connections
● Requires a simple setup
(a bit more on Windows)
Fast install
Easy setup

21. Collaboration:Aster Pronet – March 27, 2015
Simulagora – prepare to take-off...
● Write the parametrized launch script and check that :
– it runs smoothly to the end
– it produces the expected results
● Prepare the 400 runs
Technicalities
● Also possible to store run
parameters into a file per run
● Runs are recorded but not
started until explicitly
requested
● Main difficulty is to generate
the parametrized command

22. Collaboration:Aster Pronet – March 27, 2015
Simulagora – launch the complete study
● In this 1st medium-scale experiment, we had to use a conservative
computation power ramp-up (more on this later)
● Real elapsed-time for the 400 computations was 2,5 days
(total of 33 CPU days on the chosen servers - 8Go RAM, 4 CPU)
● We can now achieve the same within ≃ 5 hours (and soon a bit less)
Number of running computations over time

23. Collaboration:Aster Pronet – March 27, 2015
Phimeca's feedback (1/2)
Code Aster:
● 1h30 per simulation
● RAM 10 GB consumption
● 400 simulations to launch
Simulagora vs. clusters:
● Phimeca's internal resources may be temporarily exhausted like during the Sicodyn project
● Simulagora's pros vs. usual external clusters approach = simplicity
– No configuration or install
– No job manager
– Powerful Python API
For this kind of projects, we usually
distribute our calculations on external
clusters.

24. Collaboration:Aster Pronet – March 27, 2015
Phimeca's feedback (2/2)
Pros:
● Highly and skilled technical support
● Machine image customization to come
● Python API to distribute the computations and retrieve results (still in
development but very promising)
● Web interface to manage the studies
To improve:
● Need an even simpler Python API:
– 'Simulagora run script.py' to create and launch a study
– 'Simulagora download' to retrieve results
● No commercial offer yet

25. Collaboration:Aster Pronet – March 27, 2015
Lessons learned by Logilab
● Logilab faced and solved or worked-around real-world problems
– A bug in disk resource freeing
● Warned by Amazon because of a 20To limit reach
● Resources first freed manually
● Quick code fix
– Some computations crashed due to a high load on the web server
● Worked-around by staggering the launches
● Crashed runs re-init not easy, but a quick work-around
→ clean fix and API improve to come

26. Collaboration:Aster Pronet – March 27, 2015
Near future of Simulagora
● The Python client will shortly provide higher level operations
(suggestion from Phimeca)
● Logilab will now work on a commercial offer
We now think the service has a commercial value
● Beta-testers are still welcome !

27. Collaboration:Aster Pronet – March 27, 2015
Thanks for your attention!
Florent Cayré
florent.cayre@logilab.fr
+33 1 45 32 03 12
www.logilab.fr
Karina Macocco
macocco@phimeca.com
Felipe Aguirre
aguirre@phimeca.com
+33 1 58 51 18 11
www.phimeca.com