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Planning Mode Simulator: A simulation tool for studying ALMA's scheduling behavior


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These are the slide I used to present my thesis. The following is the abstract from my thesis:
Atacama Large Millimeter/submillimeter Array, or ALMA, is a multinational project which will be composed of around~66 radio-telescope antennas, that have to be coordinated. Observation time on this very expensive facility has to be carefully planned, allowing to use the available time efficiently for observation, reconfiguration, and maintenance.
To reach this goal, ALMA project must count with a simulation tool to allow proper study of the scheduling behaviour and configuration of the array of antennas. There are several factors that have to be included in the simulation environment, such as environmental variables, array disposition, incremental addition of antennas, failures of antennas, self-shadowing, etc.
This undergraduated thesis cover the analysis and development of the planning mode simulator for the ALMA project. A new architecture to achieve the requirements is proposed, and a first versión is successfully developed by the scheduling subsystem team. The new architecture will be re-used for the re-factoring of the scheduling subsystem.

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Planning Mode Simulator: A simulation tool for studying ALMA's scheduling behavior

  1. 1. Planning Mode Simulator: A simulation tool for studying ALMAs scheduling behavior Undergraduate thesis presentation Arturo A. Hoffstadt Urrutia Software developer, Research collaborator, <>
  2. 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. 3. IntroductionALMA antenna in a starry night, long exposure.
  4. 4. Atacama Large Millimeter Array 12m Array Simulation (!) Atacama Compact Array (ACA)
  5. 5. Operation Site Facility
  6. 6. ALMA Operation Site
  7. 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. 8. Interferometry● Smaller wavelenghts => larger antennas.● Either build bigger telescope, or use interferometry.  = D● Technique that allows to combine several sampling of the same source, to enhance image resolution.● Spatial resolution is limited by diffraction effects:
  9. 9. Interferometry ● This technique combines the signal received from two receptors, multiplying and averaging their signals.
  10. 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. 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. 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. 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. 14. Thesis ProposalMain Goal: ● “To design and develop the first iteration of the Planning Mode Simulator for the scheduling subsystem of the ALMA Project.”
  15. 15. Thesis Proposal● Specific Goals: ● Integration of the student to the ALMA Project and its 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. 16. State of Art and Practice
  17. 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. 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. 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. 20. AnalysisMilky Way blazes facilities at Mount Paranal.
  21. 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. 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. 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. 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. 25. Architecture
  26. 26. Transveral concerns● Performance, specially in network communications.● Software maintenance.● Flexible DSA.● Several input methods.
  27. 27. 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.
  28. 28. 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.
  29. 29. 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.
  30. 30. 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.
  31. 31. Conclusions and Future WorkHorsehead nebula, using the 0.9-meter telescope on Kitt Peak.
  32. 32. 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.
  33. 33. 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.
  34. 34. 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]
  35. 35. 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.
  36. 36. Questions?
  37. 37. Use cases (1/3)
  38. 38. Use cases (2/3)
  39. 39. Use case (3/3)