SIMO%20SIMulation%20and%20Optimization%20

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SIMO SIMulation and OptimizationNew generation
forest planning system

• 15.11.2005
• Antti Mäkinen Jussi Rasinmäki
• Dept. of Forest Resource Management / University
  of Helsinki

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Need for new planning system?

• Forestry databases maintained in Finland mostly
  collected either with
• National Forest Inventory
• compartment-wise inventory
• Current forest management planning packages are
  designed to suit these two data sets
• Stand volume, timber assortments and growth are
  predicted using single tree models
• In the future the data sources are much more
  variable, including data from several grain
  levels
• ? Need for new planning tools

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Aims of SIMO

• FLEXIBLE with respect to data it demands and
  models that it uses
• ADAPTABLE to the planning problem
• EXTENDABLE for possible future needs
• provide decision support for different grain
  levels

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Aims of SIMO continued

• To produce a set of lightweight program modules,
  which the users can interface into their planning
  systems
• Modules should be adaptable to different planning
  tasks and needs
• Simulation parameters can be (easily) controlled
  by the user
• Simulations can be locally calibrated
• Uncertainty in the data can be taken into account

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Aims of SIMO continued

• New models can be implemented by the user
• Possibility to utilize different data sources
• Planning system is not a black box user
  should know what happens inside the program
• Inconsistent or erroneus data can be handled, but
  the user will be informed precisely

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SIMO software development

• The core elements of the planning system will be
  produced in this project (no user interfaces)
• All the products will be open-source code (MIT
  license)
• The users will handle the integration into their
  own systems
• At the moment the simulator module is well
  underway and other modules under construction

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SIMO Simulator

• Simulator module consists of
• simulator core (the simulator program)
• XML files (data, simulation control, simulation
  logic etc.)
• Model library (all the models, functions etc.
  used in the simulations)
• Business logic and Application logic
  separated
• Other modules will be produced and integrated
  into the system

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Simulator core

• The programmatic component, contains the
  application logic

• Intakes simulation control instructions, model
  chains, model definitions and data in XML format

• Processes the user defined model chains for each
  computing unit in the data

• Calls the Model Library whenever some value needs
  to be calculated

• Prints the resulting values into a result XML file

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XML Files (eXtended Markup Language)

• Syntax definition which can be used to express
  hierarchical data
• Platform independent, self-describing
• In SIMO, XML is used for the business logic
• Passing data in and out of simulator (Data XML)
• Passing simulation instructions (Simulation
  XML)
• Encoding the simulation logic (Model Chain XML)
• Passing information of the models and variables
  to the simulator (Model XML and Variable XML)

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Model Library

• Includes all models used in the simulator

• Users can add new models to the library or create
  additional model libraries

• Reports warnings and errors to the simulator

• Risk level models not yet implemented

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Missing modules

• Optimizer module

• Finds the best alternative from the alternatives
  generated by the simulator

• Possibly many alternative optimizing methods?

• Validator module

• Validates the XML files with XSD (Schema) files
  and by external rules

• Makes sure that the XML files are well-formed and
  contain all necessary elements

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Strengths of SIMO XML Simulator

• Virtually any kind of model can be used in the
  simulations and added to the model library

• User can define the model chains freely for
  different kinds of simulations

• User can define correction/rectification factors
  for the models, (eg. different factors for
  geographical areas)

• Data levels are not confined to strict predifined
  standard

• Extensive warning and error reporting system
  (risk control coming later...)

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What can be calculated at the moment?

• Estimating forest variable development at both
  stand level tree level is possible at the
  moment (300 models implemented), but

• Forestry operations not yet implemented in the
  simulator

? real world simulations not yet possible

• Bucking models still not ready

• Optimizing module still missing

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How the simulation process works in SIMO?
XML Files
Reporter Module
IN XML data OUT transformed XML, graphs
IN data, simulation control, modelchains, model
definitions OUT results
SIMULATOR
IN modelname, input variables OUT model
result, warnings errors
SIMULATION PROCESS
MODEL LIBRARY
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What is missing?
XML Files
Reporter Module
Validator Module
SIMULATOR
Optimizer Module
MODEL LIBRARY
MODEL LIBRARY
MODEL LIBRARY
MODEL LIBRARY
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Reporting Module

• Used for visualizing data transforming the
  results from XML format to other formats

• Intakes data and processing instructions in XML
  format

• At the moment can plot different kinds of graphs
  of given variables

• XML transformations to be implemented later...

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Model risk management

• Two levels
• Individual parameter values out of bounds
• All individual parameter values acceptable, but
  is the specific combination of them acceptable?
• Case 1 already in the simulator
• Case 2 Suggestion
• get the k nearest neighbours from the VMI data,
• evaluate the model for the data point and the k
  nearest neighbours.
• If the difference for the model estimate between
  the data point and the neighbours is too big,
  generate an event of unacceptable model
  estimate

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• Isnt that procedure too heavy computationally?
• Probably, not yet evaluated
• But what about if we store the risk evaluation
  results and use those primarily
• Is it safe to call ModelA with parameters (5, 6,
  10) when we accept risk level X?
• Has the risk been evaluated with parameter values
  (5,6,10) and risk level X before. If yes, get the
  answer from a table of risk evaluations
• If not, get k nearest neighbours for data point
  (5,6,10), evaluate the model with (5,6,10) and k
  neighbours
• Store the risk evaluation result and the mean
  model result for k neighbours for the data point
  (5,6,10) and risk level X

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• Open questions
• When evaluating model result shall we compare it
  to values derived directly from the nearest VMI
  permanent sample plotsORmodel estimates for the
  nearest VMI sample plots?

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Software license for SIMO

• Types of Open Source licenses
• MIT Co Do whatever you want
• LGPL Everything you do to the original code
  must be open source, anything on top of that can
  be closed
• GPL Co Everything you do is open source,
  well almost
• GPL under the hood "derivative work" or "mere
  aggregation? Derivative work must be open
  source, but aggregation can be closed source

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• The case of MySQLDouble licensing open source
  GPL, commercial development with a commercial
  license that allows closed source

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General software architecture

• Individual components that communicate over the
  network
• Validator
• Simulator this is well underway
• Optimiser
• Reporter simulation results to figures and
  other data formats than XML, or different XML
  format etc.
• Implications to licensing? What about if one of
  the components uses a sub component that is
  published under GPL?

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Architecture continued

• TCP/IP based communication
• Security issues?
• secured traffic (SSL, SSH)
• inside firewall
• Scalable