The document describes an undergraduate thesis presentation on developing a planning mode simulator for ALMA's scheduling subsystem. It includes: - An introduction to ALMA, radio astronomy, interferometry, and ALMA's scheduling subsystem. - A review of the state of practice in site characterization, scheduling simulations, and the existing scheduling subsystem. - An analysis of requirements for the planning mode simulator including inputs, parameters, reports, and visualizations. - A proposed architecture using inversion of control and data-access patterns to achieve flexibility, performance and maintainability. - Conclusions that the first iteration of the simulator was delivered and future work is planned to add more functionality and a GUI.

1. Planning Mode Simulator: A simulation tool for
studying ALMA's scheduling behavior
Undergraduate thesis presentation
Arturo A. Hoffstadt Urrutia
Software developer, www.almaobservatory.org
Research collaborator, www.utfsm.cl
<ahoffsta@inf.utfsm.cl>

2. Agenda
● Introduction:
● ALMA, Radio-astronomy, Interferometry, Scheduling
Subsystem
● State of Art and Practice
● Site characterization, scheduling simulations,
● Analysis
● Architecture
● Desing and Construction
● Conclusions

3. Introduction
ALMA antenna in a starry night, long exposure.

4. Atacama Large Millimeter Array
12m Array Simulation (!)
Atacama Compact Array (ACA)

5. Operation Site Facility

6. ALMA Operation Site

7. Radioastronomy
● Area that studies radio waves emissions from
phenomena occurring in the outer space.
● Phenomena:
● Electrons transitions.
● Molecular vibrations.
● Molecular rotations.
● Black body radiation in the order of 1 [K] temperature.
● Synchrotron radiation.
● Dark matter.

8. Interferometry
● Smaller wavelenghts => larger antennas.
● Either build bigger telescope, or use interferometry.
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● Technique that allows to combine several sampling of
the same source, to enhance image resolution.
● Spatial resolution is limited by diffraction effects:

9. Interferometry
● This technique combines
the signal received from
two receptors,
multiplying and
averaging their signals.

10. Interferometry
● The two receptors, as seen
from the observing source
POV, form a baseline.
● More than one baseline
can be combined to
reconstruct the original
signal.
● Baselines changes as
earth rotates.

11. Scheduling Subsystem
● Purpose: ... to manage the execution of approved
observing projects.
● Input: Observing projects, Array and DSA
configuration.
● Output: Observation schedule.
● (!) Please note that this is a huge simplification of the
system.
● Observing projects are composed of several
Scheduling Blocks (SBs)

12. Scheduling Subsystem
● To construct this observation schedule, the subsystem
must count with several data:
● Wind speed and direction.
● Water vapor content.
● Available antennas and equipment.
● ALMA array configurations.
● Array baselines.
● UV coverage.
● Visibility.
● Percentage per executive, and so on...

13. Problem Definition
● Planning Mode Simulator is one of the deliverables of
the Scheduling subsystem.
● There is a basic implementation for it, but after
analysis, found it to be non-usable as it is.
● The current solution has scalabitlity and maintenance
issues.
● But, simulations concepts and code can be reused.

14. Thesis Proposal
Main Goal:
● “To design and develop the first iteration of the Planning
Mode Simulator for the scheduling subsystem of the
ALMA Project.”

15. Thesis Proposal
● Specific Goals:
● Integration of the student to the ALMA Project and it's
standards.
● Define a software development project.
● Refine necessary requirements.Define an interaction
storyboard and GUI.
● Design the Planning Mode Simulator.
● Define data models for input and output data.

16. State of Art and
Practice

17. Site Characterization
● AOS has several studies, which shows:
● Instrument that can determine precepitable water
vapour, temperature, visibility, wind, phase stability, etc.
● This data has been characterized through several
years.
● Long lasting weather effect are studied, such as global
warming, “El Niño/La Niña” cycles, and Bolivian winter.
● Studies on wind, temperature and other weather
variables according to geographic environment is also
available.

18. Radio Interferometer
Scheduling Simulation
● ALMA publications of earlier development in simulator
an DSA by Farris.
● ALMA scheduling policies addition to scheduling
subsystem by Lucero.
● One research group [5], but no publications or public
work.

19. Scheduling Subsystem
● On previous design, which was published in [6]:
● Only considers ALMA configuration and observation
project as inputs.
● Simplistic weather simulation.
● No presented results.
● Requirements for the Planning Mode Simulator can be
found in several documents.
● A refined version, with cross-reference, was created.

20. Analysis
Milky Way blazes facilities at Mount Paranal.

21. General Requirements
● Create a software that allows the study of:
● Scheduling algorithms,
● Configuration of ALMA for the observing season
● Distribution of observing projects.
● Weather simulations
● Randomization and fuzzy denomintations
● Configuration of ALMA.
● Specially growing behaivour.

22. Input and Parameters
Requirements
● Observation projects for a whole season (12 months,
18000 scheduling blocks).
● Changes in scientific rating of projects.
● Tuning parameters of scheduling algorithm.
● Consider ALMA evolution over season.
● Consider executive percentage balancing guidelines.
● Historical weather data.

23. Reports and visualizations
requirements
● Prepare a long series of reports and visualization:
● Observing modes over/under subscriptions
● Observing band over/under subscriptions.
● Allocated time per executive.
● Expected hours of observing as a function of:
– Time
– Configuration evolution
● And much more...

24. Simulations inputs and
parameters requirements
● Present data: ● Absent data:
● Observation projects. ● Weather.
● Actual array ● Executive.
configuration. ● ACA coordination.
● Calibrators. ● Sub arraying.
● Estimated time of ● Future array
execution. configuration.

25. Architecture

26. Transveral concerns
● Performance, specially in network communications.
● Software maintenance.
● Flexible DSA.
● Several input methods.

28. Dynamic Scheduling Algorithm
● Inversion of control architecture pattern as main driver.
● Four levels of independant class famalies.
● Each level has a very determined concern and interface
(uncoupling).
● Pieces in each level can be interchanged, or multiple
instances can be used.
● All these to control the scheduling blocks flow through
selection, priorization and execution stages.

29. Planning Mode Simulator
● Conceived as a library, with a CLI and GUI.
● All parameters and input data are transfered to a
common package, so that can be reused.
● Simulation logic is delegated to data-model of
observatory characterics.
● Time management is handled by the program.
● Arrays and starting and ending times are expressed in
data-models.
● Necessary configurations are taken from an XML-file.

30. Data access and persistance
● Initial data population: XML files.
● Data persistance: ORM solution.
● For each database, a common object oriented data-
model is used, and from it:
● An XML Schema Definition (XSD) is generated.
● POJO classes for in-memory representation of ORM
are generated.

31. Data access and persistance
● A broker-like design pattern will be used for
implementing intelligent cache of the ALMA Archive in
a primary-memory HSQLDB.
● Eliminates most queries currently directed to Archive.
● A primary-memory cache is far more efficient than
network access or secondary memory.
● DAOs for accessing data. If needed, conversion from
XML unmarshalled classes to ORM POJO classes is
provided.

33. Conclusions and
Future Work
Horsehead nebula, using the 0.9-meter telescope on Kitt Peak.

34. Conclusions
● First iteration is ready, and delivered to client.
● A new performance oriented architecture has been
created, and will be re-used for scheduling subsystem
as a whole.
● ALMA-UTFSM is researching new algorithms, which
will be tested using this same tool.
● Thesis done as part of ALMA scheduling subsystem, in
fact, UTFSM contributing 0.5 FTE to the project.

35. Conclusions
● More parameters and functionality to be added in next
iterations.
● Computer simulated weather, SB linkage, sub-arraying,
calibrations, ...
● GUI to be provided in coming iteration as an
OpenOffice application, with planning mode simulator
incorporated as plugin, using UNO component model.
● To achieve the necessary visualization capabilities.

36. Bibliography
● Site characterization: Alma memos series [1]
● M. Holdaway, Fast switching Phase Calibration... [25]
● J. Pérez, Analysis of wind data gathered at Chajnantor.
● S. Radford, Site Characterization and Monitoring. [35]
● Radio astronomy and Inteferometry:
● K. Jansky, Radiowaves from outside the solar system.
● B. Burke, An introduction to radio astronomy. [11]
● W. Goss, Discovery of Type I, II and III ... [21]
● Patterns:
● R. Johnson, Designing resusable classes. [27]
● State before this thesis:
● Allen Farris et. al, Scheduling Subsystem Design Document. [17]

37. Acknowledgement
● To my family, who has accompany my along this road.
● To my dear friends, who are almost my second family.
● To two dear teachers, Cecilia Reyes and Horst von
Brand.
● To my collegues, who are as much author of this work
as I am: Jorge, Rafael and David.
● This work is possible through the ALMA-Conicyt grant
#31080031, and a complementary fund granted by
NRAO.

38. Questions?

39. Use cases (1/3)

40. Use cases (2/3)

41. Use case (3/3)