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Powersim Studio 10 released

Postby Leonard Malczynski » Wed Apr 09, 2014 10:00 am

Powersim AS has released Powersim Studio 10 (http://www.powersim.com)
There are many new features and improvements. A more thorough list can be found at the website.

Examples:
-free Studio Cockpit model distribution
-expanded connections to file-based databases
-a new method CreateActiveXObject for the external object available to the HTML document contained in Presentation Sidekicks and in the dialog of Show Dialog actions.
-a new method Simulation::SetMultipleValues in the Simulation Engine Object Model that makes it possible to change the value and/or history of multiple variables
-a new function PERIODLENGTHSERIES that returns the length of all series periods as a vector.
-revamped the password protection scheme
-introduced an option named 'Enable Active Content'
-possibility to limit the number of cores utilized for calculations per simulation project.
-the Oil Production Simulation sample has been updated to use the CreateActiveXObject method
-new sample model: The Upstream Oil and Gas Simulation model illustrates assembly of a model using components from a component library.
-a link to on-line instructional videos in both the Task Assistant and the Help menu.

Regards,
Len Malczynski
group moderator of the independent Powersim Tools User Group (https://groups.yahoo.com/neo/groups/powersimtools/info)
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STELLA and iThink 10.0.5 Now Available!

Postby Karim Chichakly » Sun Mar 23, 2014 4:26 pm

isee systems is pleased to announce that STELLA 10.0.5 and iThink 10.0.5 are now available (http://www.iseesystems.com). This new update runs models faster than ever and also includes minor enhancements to the user interface. A full list of changes to 10.0.5 is available at http://www.iseesystems.com/softwares/Version1005Fixes.aspx. If you are new to version 10, please visit http://www.iseesystems.com/softwares/Version10Features.aspx.

To celebrate this improved version of our XMILE-compatible System Dynamics modeling package, we are offering a 20% discount on all upgrades from versions prior to 10.0 and a 15% discount to System Dynamics Society Forum readers on cross-grades from other System Dynamics modeling packages. Please contact us at support@iseesystems.com if you are interested in a quote. Please hurry; this offer ends soon.
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Aivika of version 1.1

Postby David Sorokin » Sat Mar 08, 2014 2:40 am

It might be interesting to the modelers who have strong skills in the programming. Here I am glad to announce Aivika of version 1.1.

Aivika [1] is a multi-paradigm simulation library with a strong emphasis on the Discrete Event Simulation (DES) and System Dynamics (SD). It is written in the Haskell programming language. While the support of DES is quite extensive, System Dynamics is well supported too.

So, you can define the recursive stochastic ordinary differential equations (ODEs) almost in the same way as in specialized modeling tools like Vensim. The equations even may look similar.

Here is an example [2] that I took from the documentation of Berkeley-Madonna (the 5-minute tutorial). It returns the integral values in the final simulation time point.

This is the same model [3], only now the calculated data are automatically saved in files and the charts are plotted as well as an HTML page is generated, and all this is fully described in the stated Haskell file. You can observe the results in your favorite Internet browser.

Another example [4] corresponds to the model described in Chapter Financial Modeling Risk of Vensim 5 Modeling Guide. It uses a Monte Carlo simulation that depends on external random parameters. As before, you can observe the simulation results displayed as charts and histograms in your Internet browser. So, the deviation chart is displayed (using the 3 sigma rule).

You can use the Design of Experiment (DoE) as well. There is nothing special with it. Just use functions tableParameter and memoParameter of the Parameter module.

Aivika actually provides an Embedded Domain Specific Language (eDSL). Therefore, you can use all the power of so very high-level and general purpose programming language as Haskell. Aivika makes the latter much more close to the modeling language (there is quite an opposite tendency when other developers are trying to make their modeling language more close to the general purpose one as in SimScript).

The arrays (and more modern vectors) are naturally supported by Haskell itself. There is nothing special too. Only you should be skilled in using so called the recursive do-notation. Namely this notation allows defining the recursive ODEs as in maths.

This model [5] demonstrates the use of arrays as described in model Linear Array from Berkeley-Madonna.

The difference equations are supported too. The model [6] corresponds to the tutorial of Berkeley-Madonna.

A few words about the speed of simulation. The integrating of ODEs is quite slow (about in 15-20 times slower than it could be without combining with DES). At the same time, the DES support is rather fast and namely DES is the main feature of Aivika.

The DES and ODEs can be combined within one model as everything is well integrated in Aivika and uses the same basis, the same mathematical formalism I found.

The integrals can be directly used in the DES model (through function liftDynamics). Now only such integrals are supported that must be calculated in all integration time points, which may lead to consuming much memory and degrading the performance. Therefore; sometimes it makes sense to define the integration method directly in the model as in the Furnace model [11].

An opposite direction from DES to SD is a little more complex. The modeler can use the Var data structure that has a mutable state, usually updated from DES, and that saves the history of its values (only the last change is saved for every time point). Then the Var variable can be used in the differential equations. Please read more details in the documentation of the Var module.

Finally, a few words about DES. Aivika supports very different paradigms of DES from event-driven [7] to activity-oriented [8] to process-driven [9] and even to that one which I invented and which name I do not know yet. It is possible to define the model [10] as a workflow in terms of queues, servers (the working places), infinite streams of data and processors that operate on them. Then the model can be read as you would define it on the diagram. As before, all the DES is well integrated in Aivika (through the event queue).

I’m looking forward to receiving your feedback.

Kind regards,
David Sorokin <david.sorokin@gmail.com>

Yoshkar-Ola, Russia

[1] http://hackage.haskell.org/package/aivika
[2] https://github.com/dsorokin/aivika/blob/master/examples/ChemicalReaction.hs
[3] https://github.com/dsorokin/aivika-experiment-chart/blob/master/examples/ChemicalReaction.hs
[4] https://github.com/dsorokin/aivika-experiment-chart/blob/master/examples/Financial.hs
[5] https://github.com/dsorokin/aivika-experiment-chart/blob/master/examples/LinearArray.hs
[6] https://github.com/dsorokin/aivika-experiment-chart/blob/master/examples/DifferenceEquations.hs
[7] https://github.com/dsorokin/aivika/blob/master/examples/MachRep1EventDriven.hs
[8] https://github.com/dsorokin/aivika/blob/master/examples/MachRep1TimeDriven.hs
[9] https://github.com/dsorokin/aivika/blob/master/examples/MachRep1.hs
[10] https://github.com/dsorokin/aivika/blob/master/examples/SimpleWorkflow.hs
[11] https://github.com/dsorokin/aivika-experiment-chart/blob/master/examples/Furnace.hs
David Sorokin
 
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Simile v6.1 released

Postby Jasper Taylor » Mon Feb 10, 2014 5:27 am

Simile version 6.1 released

This minor version adds some useful new functionality to http://www.simulistics.com/simile-v60-released. Note: a patch release was made on 7th February 2014 correcting a few problems identified after the release.

Much easier to make spatial interaction models

Previously, when using a 2-D array submodel to represent a spatial grid, it was necessary to create a self-association submodel to allow data to be past between instances representing neighbouring grid squares or hexagons. Now there are pre-defined submodel types for these common constructs, inside which you can set link properties to move data between neighbours.

Layered spatial-mapping display tool

There is a new display tool that works a bit like a GIS display, in that representations of several data sets can be superposed on each other in the same window to create composite diagrams. The layers available include rectangular and polygonal maps, and an all-new one for displaying individuals with locations on the maps as icons.

element() function works on lists

The element() function is Simile's way of selecting element(s) from an array or list. Formerly, the first argument of element() had to be an array, because values had to be looked up directly by their indices. Now the first argument can be a list (a value from a variable-membership submodel such as a population) and the result is a sublist, generated by seeking through the list and adding all the values whose indices appear in the second argument.

element() function takes multiple indices

If you have a 2-D (or higher) array, you can look up a single member by using element() with 3 (or more) arguments, e.g.,

Code: Select all
element([[arr]], x, y)


Formerly you would have had to do this by nesting element() calls, but the new format is neater and allows the indices to be matching arrays or lists themselves to get multiple values.

Faster processing of association relationships

Simile uses a method called "base instance lookup" to speed up the processing of associations between submodel instances. Previouslly only 1-dimensional fixed-membership submodels could have instances looked up rather than searched for when building an association. Now, the extra functionality described above for element() allows instances of any submodel type to be looked up, so associations can be built faster.

Download Simile v6.1 now! http://www.simulistics.com/products/simile.php
Jasper Taylor
 
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New SD KickStarter - Approachable System Dynamics

Postby Robert Powers » Sun Dec 22, 2013 11:12 am

Approachable System Dynamics aims to bring classical stock and flow modeling and existing SD models to the web, in 2 parts. The fist part is an open-source simulation engine that runs and displays existing and new models in high fidelity, and integrates with other web technologies and ebooks. The second part is a free online modeling service that allows people to upload and share existing models, and create new ones. The KickStarter rewards involve early access to the modeling platform, and compatibility testing for models of your choosing.

Image

Currently, the following is done & working:
    Simulates simple XMILE models in Firefox, Chrome and Safari
    Displays stock-and-flow diagrams
    Basic zoom + navigation
    Simulate modules
    Overlays simulation results on the stock and flow diagram
    Several built-in functions
With this Kickstarter, I can complete what is next:
    Compatibility testing with existing models
    Display & edit equations
    Unit checking
    Internet Explorer simulation support
    Vensim import
    Runge-Kutta integration
    Built-in live simulation (like SyntheSim and STELLA Live)
    Multidimensional arrays
    The rest of the common and uncommon built-in functions
    Display modules & 'zoom in' to them
    Documentation., both the API for programmer types, and higher level documentation for modelers looking to embed their models in ebooks or on websites.

Visit the KickStarter page here for more information: http://www.kickstarter.com/projects/1838712738/approachable-system-dynamics
Robert Powers
 
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Insight Maker 4.0 Released

Postby Scott Fortmann-Roe » Thu Aug 08, 2013 12:08 pm

We are pleased to announce the release of Insight Maker 4.0: the powerful on-line simulation platform. The following major features have been added to Insight Maker since version 3.0:

  • Vector Primitives (Arrays): You can now easily vectorize primitives in your models to represent different categories or classes of behavior. (Video Overview)
  • Optimizer: Automatically search through your parameters to find the set of values that best fits historical data or to maximize or minimize some goal.
  • Storytelling: Guide your audience through your model step-by-step. Reveal primitives, expand folders, and provide messages to highlight the key parts of the model.
  • Power Programming: You could always use Insight Maker's equation language to augment Insight Maker's capabilities with new functions. This equation language has now been greatly extended to support Functional and Object Oriented programming. Closures, anonymous functions, prototype-based inheritance, and more; it is all there now.
  • Much More: Many minor improvements, enhancements and optimizations have been made to Insight Maker with a focus on ease-of-use. These include:

    • Improved touch and tablet support,
    • Sketching support for converter graphs,
    • String manipulation support,
    • Improved error messages and error handling,
    • Additional simulation functions,
    • Extended documentation,
    • Primitive rotation and other diagram enhancements,
    • and more...

These features are added to Insight Makers extensive set of existing modeling and simulation capabilities which include:

  • Web interface to build and runs models without software download needed
  • System Dynamics Modeling
  • Agent Based Modeling
  • Sensitivity Testing Tool
  • Extensive Units Support
  • 1st Order and 4th Order differential equation engines
  • Macros and Scripting Features to extend the capabilities of Insight Maker
  • The ability to share a model as a webpage simply by sending a link
  • Insight Maker is Free and Open Source

You can get started with Insight Maker for free at http://InsightMaker.com

Image
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New Version of SDM-Doc (ver 4.9.6) Now Available

Postby Ignacio Martinez-Moyano » Thu Aug 01, 2013 1:03 pm

A new version of the System dynamics model documentation and assessment tool SDM-Doc is now available.

To download it, please go to: tools.systemdynamics.org/sdm-doc/

Suggestions for improvement, feedback, questions, and comments are always welcome.

Ignacio J Martinez-Moyano
Argonne National Laboratory
University of Chicago
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True 2013.03.16 Released

Postby Patrick Houel » Tue Mar 19, 2013 11:18 am

True 2013.03.16 Released

I am pleased to announce the release of True 2013.03.16 (Temporal Reasoning Universal Elaboration)

http://www.true-world.com/ is a free System Dynamics software (freeware)

It enables you to build System Dynamics models by installing a single program.

New features :

- you can now backup, upload and download (sharing) your models
- you can now import a Vensim model (not all the functions can be translated and not all the models can be imported)
- new interface and new toolbars
- new stock and flow appearences
- new stock and flow shadows with dynamic causality links
- new multi view
- new functions : SetGlobalProcedure, CallGlobalProcedure, SawtoothN/P, Triangle/S/Cos, SinusPulse
- new 3D primitives : Bones, SuperTorus, Fountain

Illustrations :

shadow.gif
stock and flow shadows with dynamic causality links
shadow.gif (214.35 KiB) Viewed 6048 times


spider.gif
Spider made with bones
spider.gif (19.76 KiB) Viewed 6048 times


All the best,
Patrick Houel
patrick.houel@true-world.com
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New version: C-Learn simulation for the web

Postby Roberta Spencer » Tue Feb 05, 2013 6:48 am

From The Climate Interactive team:

We are pleased to announce the launch of a new version of the C-Learn simulation for the web.

C-Learn enables you to explore the level of emission reductions it will take to address climate change across three different groups of countries. This updated version is built on a new platform, so those familiar with the old version of C-Learn will notice slight changes to the interface. The Forio Simulate platform that we have switched to allows you to embed the simulation on an existing website and create a free account to save your scenarios for later.

We've also improved the ability to use C-Learn for running the World Climate Exercise and added a new feature that calculates how annual emission reductions equate to the percent change above or below 2005 levels of CO2 in 2050.

To check out the new version of C-Learn, run the World Climate Exercise, watch an introduction video to C-Learn and more, please visit http://www.climateinteractive.org.

All the best,
The Climate Interactive team
Email: info@climateinteractive.org
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Vensim 6.0b

Postby Thomas Fiddaman » Fri Dec 07, 2012 4:07 pm

Vensim 6.0b is now available for download or purchase in the Vensim store. This is a minor release, adding CSV import/export functionality and containing improvements to the treatment of data keywords and WITH LOOKUP variables, Mac bitmap display, and other bug fixes.
http://vensim.com/download/
http://vensim.com/store/

Version 6.0 introduced a new look and new features, while preserving language and file compatibility with older releases.
- Interface Changes
- A new Equation Editor layout
- Improved Toolbars and Cursors
- Optimization Features
- Stochastic optimization : optimize over an envelope of Monte Carlo simulations
- Discrete constraints on optimization parameters, so you don’t waste time determining whether to build 2.6 or 2.7 factories.
- Extended payoffs with non-Gaussian errors, logarithms, and mixed calibration/policy variables.
- Markov chain Monte Carlo & simulated annealing
- Extended payoff report information with MAPE and Theil statistics
See http://www.vensim.com/documentation/version_6_0.htm for the full release notes, with a video introduction at http://vensim.com/video.html.

You can upgrade to the latest version of Vensim easily – just follow the Upgrade link at http://vensim.com/download/ and enter your license code. Can’t find it? No problem – contact us for help.

If you don't have a recent version of Vensim, there are some interesting new features, including:
- Significant upgrades to the Help system, including improved indexing and nearly 100 sample models illustrating the use of almost every built-in function
- Native Mac support (licenses are portable across platforms)
- GET DIRECT functions that can access spreadsheets and other delimited data files, like the GET XLS functions without the overhead of launching Excel.
- The option of observing integer constraints in the ALLOCATE AVAILABLE function
- great for managing allocation of discrete items like customers or aircraft.
- Enhancements to the document tool and SyntheSim functionality with lookups in large models
- On-the-fly configuration of subscripts (arrays) with the GET DIRECT SUBSCRIPTS or GET ODBC SUBSCRIPTS functions
- great for matching model detail to your data.
- :EXCEPT: statements that let you handle exceptions to subscripted equations more easily.
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