Posts Tagged ‘netsim’

What’s New in isee NetSim 1.1?

May 17th, 2010 No comments

netsim_app_iconLast week, we released version 1.1 of the isee NetSim software.  isee NetSim enables iThink and STELLA users to publish their models online so anyone can run them in a web browser.  Version 1.1 introduces several new features.  In this post I will share a couple of those that I am most excited about.

Forio Simulate—Like YouTube for Simulations

Since the debut of the isee NetSim software we have collaborated with Forio Business Simulations to provide free hosting for models published online.  Last year, I saw a demo of Forio’s new simulation service, Forio Simulate, in the early development stage.  It was awesome.  I couldn’t believe it—they added all of the Web 2.0 features I’d been dying for, and a slick, fun to use interface.  I knew we had to make isee NetSim work with it.

The new service is social by nature—it features keyword tagging, ratings, comments and built-in model sharing.  It’s like YouTube for simulations.  You can browse simulations and games that others have created, find similar ones by keyword tags, and embed simulations on blogs or web pages.  So you don’t have to be actively publishing your own simulations, or even be a modeler to get a lot of value from the site.  In fact, it’s a great way to introduce people to modeling and simulation.  Just post a link!

And if you are a modeler, you can get even more out of the service.  Most of the simulations published to Forio Simulate allow you to download or copy the underlying model that powers it.  Here at isee, we’ve uploaded the original iThink and STELLA models used to create all of our sample isee NetSim simulations.  That way anyone can run the simulation online in a browser and download the source model to dig into if they want more.  Take a look at isee systems’ models published on Simulate by clicking on the screen shot below.

The simulation overview page allows anyone to download the source model, rate, comment, add tags and embed the simulation on other web pages.

Anyone can use free hosting on Forio Simulate if the model contains 400 or fewer equations and is shared with other users of the service.  If you want to protect the model, resell a simulation, use a custom URL, etc., you can sign up for a premium hosting plan.  It’s easy to select a hosting plan when you upload your model with isee NetSim.

Graphical Input Device

Graphical Input Device, or, GID

Use the GID to change the price assumption

One of the most requested features for isee NetSim has been the graphical input device, or “GID” as we like to call it.  GIDs offer a simple way to allow people running your simulation to change the model assumptions.  Often it’s easier to sketch a curve of the behavior of a variable than to input numbers directly.

For example, the model below is a generic renewable-resource model that enables you to experiment with yield and price of a renewable-resource via GIDs.  The model is from our “Thinking in Systems” online course.  I published the model to Forio Simulate and then embedded it here.  Click the “Review model” link to take a brief tour of the model.

You can change the price elasticity and “yield per unit capital” curve by first clicking on one of the GIDs.  A window will pop open that displays the details of the curve.  Click and drag within the grid to draw a new curve.  Press “Ok” to apply the changes.  Take a few moments to play around with the model below.

[Editor’s note:  If you cannot see the embedded model below because you are reading this post in a feed reader or email, please visit the post page here]

What I find interesting after playing with this model is what happens when you start to push the yield up.  At some point the efficiency improves to the point where the renewable-resource gets completely wiped out.  Sometimes the inefficiencies of harvesting a resource can be a good thing—it gives the resource time to “catch up”.  This may be a useful point to consider when thinking about sustainable systems.  What happens when you make the resource inexpensive?

A GID for the web

You may have noticed that the GID within isee NetSim does not allow a user to type numbers to define data points or change the x and y ranges.  We decided this simpler version of the GID was a good fit for models published to the web and would cover most use cases.  The GID allows users to easily change the assumptions by sketching a behavior pattern and not really concern themselves with the data.

If you’ve been dying to publish models with GIDs online, now is your chance.  While you’re at it, check out Forio Simulate and start contributing to the growing simulation community.  You can download a trial of isee NetSim 1.1 here.  If you already own isee NetSim, visit your “My Software” page on the isee systems website to download the upgrade.

Modeling H1N1 Flu Outbreak

November 13th, 2009 3 comments

H1N1 Virus It seems like everyone has been talking about H1N1 (swine flu) the last couple of months.  If you have children in school, then you are probably very aware of how fast the virus is spreading.  Schools are the perfect environment for a virus to spread.  To help understand why, we created a STELLA model of a high school that introduces the H1N1 virus.  You can experiment with vaccination and “stay at home” policies to limit the spread of the flu.

The STELLA model is based on the SEIR compartmental model that epidemiologists use to model the progress of an epidemic.  SEIR models divide the population into compartments: Susceptible, Exposed, Infected and Recovered.  These ‘compartments’ translate nicely into stocks within the STELLA model where we can observe the dynamics of the spreading virus.

While developing the model we decided to explore some strategies that schools are pursuing to limit the virus’ spread.  We wanted to know if the “stay at home” (when you are sick) policy would be effective in the case where vaccines are not available quickly enough, (which as of November 2009 is the case).

Take a look:

Click the ‘Simulate’ link on the home screen above and try some different scenarios.  Be sure to click the ‘How does this simulation work?’ link for a guided tour of the model behind the simulation.

As you experiment with the simulation, consider the following:

  • How does varying “% vaccinated” effect the number of sick students?
  • How many days do infected students need to stay home to have a significant impact on the spread of the virus within the school?
  • What impact does the “% effectiveness of vaccine” have on the flu outbreak?
  • What combination of decisions results in the lowest number of sick students?  Are these decisions realistic in a real-world setting?

Note: Each time you dial in parameters and press run, a new plot will be added to the graph so you can compare the effectiveness of the different decisions.  Clicking on the blue reset button will clear the graph and reset all Knobs to their default value.

If you think this simple model is useful, feel free to share it or embed it on your own website; just click the sharing icon in the lower right corner.  If you want to dig deeper into the STELLA model you can download the model by clicking here.  You can open the model with STELLA 9.1, or the free isee Player.

C02 in the Atmosphere Behaves Like a Bathtub

October 16th, 2009 No comments

Last Friday we hosted the first of a four-part web seminar series titled Modeling for Environmental Sustainability.  This first session was about how you can use simple bathtub dynamics to understand climate change.

co2_bathtub In the session, Chris Soderquist demonstrates how you can use embeddable simulations to help raise awareness and understanding about climate change.  Using simple bathtub dynamics, the “C02 Dynamic Indicator” simulation lets anyone experiment with the current set of policy proposals for capping and reducing emissions.

The live session was recorded and is now posted on our website, along with two embedded simulations that you can run online.  All of the session materials are open source and we encourage you to link, embed and share them with others.

Download the isee NetSim Template Model

August 21st, 2009 3 comments

A few months ago, we designed an interface template for our isee NetSim sample models.  The template is an iThink/STELLA model in which the interface layer is designed to look like a website:

  • Navigation buttons are styled to look like hyperlinks instead of push buttons.
  • Push buttons are used to perform actions, such as running the simulation.
  • Tabs along the top of each page let the viewer know which section they are in, as well as providing a way to quickly jump to any section.

An example of the interface template applied to a model published online

You can download the template model and use it as a starting point for creating interfaces to models you want to publish online.

Download the template for STELLA

Download the template for iThink

How to use the template

The template model consists of four interface pages: Home, Background, Explore Model and Simulate.  Navigation buttons to and from each page are already setup within the interface.  You can customize each section by replacing the placeholder text.  The pages are a starting point that establishes a website-like look and feel.

The easiest way to apply the template model’s interface to your own model is to simply copy and paste the pages.

  1. Open your own model and switch to the Interface layer.  Choose ‘Interface Prefs’ from the Interface menu and make sure the ‘Show Pages’ option is selected.  Set Page Size to 800×600.  This will allow you to see the page boundaries as you apply the template.
  2. Open the template model and from the Interface layer choose the Edit menu –> Select All, then Edit menu –> Copy to copy all of the pages to the clipboard.
  3. Go back to the interface layer of your model and choose Edit menu –> Paste.

When you have pasted the pages into your model, they will probably not be lined up correctly within the page boundaries.  The dashed lines show the boundaries of each page.  Using these dashed lines as a guide, use the arrow keys on your keyboard to make the pasted pages line up properly.

Now you can customize the title and text in each page.  Add a picture to the home page and build a control panel.  If you want, you can use the hyperlink button on the ‘Background’ page to link to online information, (PDFs, other models, Wikipedia, etc.).  Consider building a storytelling sequence on the ‘Explore Model’ page to unfurl the model a chunk at a time.  These are just a few customizations you can make.  Take a look at some of our sample models published online with isee NetSim for ideas.

If you publish some models online that use the template, we’d love to see them!  Leave a link in the comments so we can check them out!

Categories: Modeling Tips Tags: , ,

Rethinking ‘Cash for Clunkers’

August 11th, 2009 2 comments

C.A.R.SThere is no doubt that the Car Allowance Rebate System, or “Cash for Clunkers” program has proved to be popular with American car buyers.  So popular in fact, that it ran out of cash within the first six days of processing claims.  This news got me thinking about the program in a more systemic way.

Whether you think of the program as a stimulus for the economy or the environment, it cannot continue to operate without funds.  Congress had to quickly approve another $2 billion for the program when the initial $1 billion appropriation was exhausted in less than a week.  The rebate fund lacks an inflow of cash to offset the outflow of payments.

I wrote about a STELLA model of a self-financing program to promote cleaner vehicle sales in May.  The “Feebates” model uses fees charged on sales of vehicles that have high pollution rates to finance rebates for cleaner vehicles.  I asked the Feebates model author, Andrew Ford what he thought about “Cash for Clunkers”.  He sent me an article he co-authored with Todd BenDor titled “Simulating a combination of feebates and scrappage incentives to reduce automobile emissions”.  Basically, the article describes a feebates model with a “cash for clunkers” type of rebate added to promote scrapping older vehicles.  The article was published in the journal Energy, 31(2006), 1197-1214.

3808715790_393164d861Mr. BenDor was kind enough to send me the STELLA model so we could publish it to the web with isee Netsim.  We thought this would be a great way to start some discussion around the Clunkers program, public policy and using simulations to facilitate decision making.

Click here to run the simulation online.

  • Can you design a policy that stimulates the economy and reduces emissions?
  • This simulation uses fees to fund the program instead of deficit spending.  What other sources of revenue could we consider?
  • Many states levy a “sin tax” on tobacco and alcohol.  How would the public react to fees on high-pollution vehicles?

Post your answers in the comment section below.

Image credit:

Insight-based Model Investigates the Housing Crisis

May 5th, 2009 3 comments

wpi-logoFor the past few months I’ve been taking a distance learning course at WPI called “System Dynamics Foundations: Managing Complexity”. The course covers a broad range of topics about the system dynamics methodology and how it has been applied in the real world.

One of the things I really like about the course is the different perspective the instructors bring to the table (or in this case my computer screen.) Last week’s lecture focused on three different styles of system dynamics modeling – Causal Loop Diagrams (CLDs), insight-based models and calibrated models.  While both instructors agreed there is value in all three approaches to dynamic modeling, there was clearly a difference of opinion about what is required to actually DO something with a proposed solution to a problem.

The topic got me to thinking about the types of STELLA and iThink models that are being built and how they are being used to DO something about real world problems. I would guess that the majority of the models fall into the insight-based category.   One of the reasons we put so much effort into creating communication features in our software is so that those insights can be shared and discovered by others.  The “ah-ha” moments that come from experimenting with simulations are often a great vehicle for getting conversations going about a particular issue and discussing possible solutions.

Read more…

Cleaner Vehicles through Fees & Rebates

May 4th, 2009 1 comment


Imagine you have been asked to design an incentive program to promote the sale of cleaner vehicles in your city. You are convinced that purchase price incentives are the key to shifting consumer choices. You believe a large rebate could encourage the purchase of electric cars and other alternative-fueled vehicles.

This is the background story for an online simulation that allows students to experiment with applying fees and rebates to automotive sales to help reduce air pollution.

As the player, your job is to manage a “feebate” program for the city that will help reduce vehicle pollution.  The program offers large rebates on purchases of cleaner vehicles, (electric vehicles, hybrid-electric vehicles and vehicles fueled with compressed natural gas) and imposes fees on vehicles that have high pollution rates.

Read more…

Medici’s Lever – An Online Cultural Policy Game

April 2nd, 2009 No comments
Medici's Lever consists of educational games and a freestyle laboratory that enables users to set game parameters

Medici's Lever consists of educational games and a freestyle policy laboratory

A couple of months ago, Steve Peterson came by the office and showed me an online game created with iThink and isee NetSim called Medici’s Lever.  I was really impressed.

The game begins in San Jose, California.  Dr. Lilia Maria Delgado, a legend of Silicon Valley’s rise to high-tech super power, has died and left a half-billion dollars to establish the “Delgado Arts Endowment”.  In her will, Dr. Delgado simply states that the mission of the Endowment is to advance the cultural life of San Jose.

Your job is to fulfill the mission by experimenting with the various approaches of five different CEO candidates over a 40 year period.  Each candidate personifies a different theory of arts and cultural development and provides you with different investment levers that impact overall “cultural vitality”.

The San Jose Rennaissance is one of two educational games that are a part of Medici’s Lever.  The other game is very similar but takes place in a different region — this time a fictitious European city dubbed the Capital of Culture.

The final module of Medici’s Lever is an interactive Policy Laboratory that lets the user “dial in” initial parameters to define the region in which they want to experiment.

The 3 elements of the "logic model" are displayed as a pyramid in the games

The 3 elements of the "logic model" are displayed as a pyramid in the games

Medici’s Lever is powered by an underlying iThink model (although users are unaware of this).  The games inform the player that it is driven by a “logic model” they must keep in mind when experimenting.

The premise of the logic model is: In order to maintain a healthy cultural ecology a region must strike a balance between three elements — cultural literacy, participation in cultural expression, and consumption of professional cultural goods and services.

In the games, the three elements are visualized as a pyramid.  What I found out after a couple of runs is that investing in the bottom of the pyramid pays off in the long-term.  The insight I gained was that a community needs to have people who appreciate art and culture and actively participate in it from a young age to be successful supporting the professional artists. In other words, it does not make sense to invest in a state-of-the-art performance hall if no one wants to attend the performances.

I think Medici’s Lever is an excellent example of how you can get folks thinking about a systemic issue in an easy and engaging way.

Background and Development

Medici’s Lever is the final project of Cultural Initiatives Silicon Valley, an organization that worked to implement a ten-year cultural plan for Silicon Valley from 1996 to 2006.  John Kreidler, Cultural Initiatives’ retired Executive Director, is responsible for the model concept and design.  The iThink model and web interfaces were developed by Steve and published online with isee NetSim.


It is important to note that at its inception, Cultural Initiatives planned to operate for one decade only.  As the end of that decade approached, John and Steve began working on bringing all of the ideas of the foundation together in a model that could be played as a game.  It was key that the game live online so others could benefit from the insights of the foundation long after it had sunset.

When Steve started developing the iThink model for the game, isee NetSim was in its beta cycle.  We worked together to see if at this beta stage isee NetSim was up to snuff for creating the type of online game that he envisioned. During the process, Steve gave me a lot of valuable feedback on isee NetSim (and rooted out quite a few bugs too).

isee NetSim turned out to be a good fit.  Steve has been using iThink for a long time so he knows it well.  isee NetSim enabled Steve to do all of the interface design inside iThink itself and let isee NetSim take care of converting it to run over the web.  Since the games could now be run in the browser, players would not need to download and install software to play the game.

Steve told me that the game is intended for policy makers, community leaders, educators, artists, business leaders — anyone who should be thinking about the role of arts and culture within a community.  I asked him how he thought Medici’s Lever would be used.

From my perspective, a game like this provides an excellent vehicle for focused discussion about arts & culture policy.  Medici’s Lever surfaces a host of questions about what is necessary to build a rich, sustainable cultural landscape.  It provides a rich context for informed discussion. Models like this are not “true” in an objective sense, but they have great potential utility.”

Freestyle allows the user to "dial up" conditions for real metropolitan regions anywhere in the world.

Freestyle allows the user to "dial up" conditions for real metropolitan regions anywhere in the world.

This is an interesting point about models in general.  This game is fictitious, but the dynamics are useful.  By allowing players to dial in different initial parameters (population size, immigration, birth and death rates, social cohesiveness and several cultural factors), users can create conditions for real metropolitan regions anywhere in the world.

Another important point is that the model runs over the web.  This makes it easy for people who are thinking about these issues to interact with the games and lab and have an informed discussion.  Players do not need a background in modeling and system dynamics. And they don’t need to download and install software.

If you want to experience Medici’s Lever for yourself, click here to play the game now.