Recent Open Source Physics Releases

GR Kerr

Sun, 16 Jun 2013 14:25:56 EST

Resource Title: GR Kerr Exploding Program
Author: Parampreet Singh

Very nice simulation

Re: Re: How to track the Calibration Points

Thu, 06 Jun 2013 10:35:45 EST

Open Source Physics Forum: Tracker
Thread: Track Calibration Point Pair
Author: Martin Peters

Great idea!
I'll check this out soon.
Thanks!

Addressing learning difficulties in Newtons 1st and 3rd Laws through problem based inquiry using Easy Java Simulation

Wed, 05 Jun 2013 16:55:14 EST

This paper describes an Easy Java Simulation (EJS) model for students to visualize Newtons 1st and 3rd laws, using frictionless motion and a spring collision during impact. Using Physics by Inquiry instructional (PbI) strategy, the simulation and its problem based inquiry worksheet aim to enhance learning of these two Newtonian concepts. We report results from Experimental (N=62 students) and Control (N=67) Groups in 11 multiple choice questions pre and post tests, conducted by three teachers in the school. Results suggest, at 95 percent confidence level, significant improvement for concept of Newtons 1st Law while not so for Newtons 3rd Law. A Focus Group Discussion revealed students confirming the usefulness of the EJS model in visualizing the 1st Law while not so much for the 3rd Law. We speculate the design ideas for constant velocity motion in the computer model coupled with the PbI worksheet did allow for making sense and experiencing of the 1st Law, where traditional pen-paper representations could not.

Re: How to track the Calibration Points

Wed, 05 Jun 2013 11:13:09 EST

Open Source Physics Forum: Tracker
Thread: Track Calibration Point Pair
Author: Douglas Brown

Martin, there's no way to have the autotracker automatically skip frames in which it fails to find a match. But if you only need one point per revolution you might be able to set the video clip start frame and step size in such a way that the only frames included in the clip are those in which the tracked point is visible.

Doug

Re: Re: How to track the Calibration Points

Wed, 05 Jun 2013 04:33:35 EST

Open Source Physics Forum: Tracker
Thread: Track Calibration Point Pair
Author: Martin Peters

Thanks for this fast answer, Doug!

If I do it like you said it's working! Great!
And yes I'm using the latest version.

Maybe you can help me with another problem as well? I want to measure a revolution speed and therefore tracked a rotating point. When the autotracker gets to a frame in which the tracked point is not visible it stops and asks if I want to skip the frame.
Because one successful track per turn is enough for my revolution speed measurement I don't care about this question which interrupts the search.
Is there any possibility to skip these frames automatically instead of clicking each time "skip" manually? This would speed up my work with "Tracker".

Best regards
Martin

Re: How to track the Calibration Points

Tue, 04 Jun 2013 12:39:02 EST

Open Source Physics Forum: Tracker
Thread: Track Calibration Point Pair
Author: Douglas Brown

Martin--are you using the latest version (4.80) of Tracker? If not, I recommend you update.

After you have marked the calibration points, you should open the autotracker by clicking the autotracker button on the toolbar (to the right of the "Create" button). In the autotracker, set the Target Track to the calibration points track and Target Point to either point 1 or point 2. Then you need to shift-control-click the video to create a key frame for the autotracker (even though the point has already been marked--key frames and marked points are not the same thing!).

Now you should be able to use the Search button(s).

Does this solve the problem? Doug

Enabling Gravity Physics by Inquiry using Easy Java Simulation

Tue, 04 Jun 2013 10:59:00 EST

Studying the gravitational physics of the solar system is difficult in real life. This paper describes four pedagogical computer models that we have developed for active inquiry instruction in Singapore. These models are now being pilot tested in Singapore and are being improved through feedback from students and teachers. We hope other teachers will find these simulations useful and further customized them for the educational community.

Re: Compilation error

Tue, 04 Jun 2013 08:07:15 EST

Open Source Physics Forum: EJS Modeling
Thread: Compilation error
Author: Man Tol

Disregard this post. Problem has been resolved by using code generator of version 1.5 instead of version 1.6.

How to track the Calibration Points

Tue, 04 Jun 2013 07:47:33 EST

Open Source Physics Forum: Tracker
Thread: Track Calibration Point Pair
Author: Martin Peters

First of all: Thanks for this great tracking tool! It's very easy and fast to use.

But I got a problem with tracking the Calibrations Points. So I created the points as the help-pdf says and marked them with the shift-click. Now I want these points to stay at the points of interest although they move in the video. So I thought let these points become trackpoints. But they keep their position and when I open the Track-menu and choose Calibration Point A it says: "Please click the video feature you wish to autotrack. Mouse over the controls above to learn more..."
But I already chose the points of interest. So I don't know why the search-button is grayed out.

Hints and help welcome.

Thanks!

Martin

Edit: My aim is a coordinate system which tracks a moving object

And how can I define a second key frame? I want to track two points of a moving object and I am searching for a solution without a second masspoint (because the tracking of 1800 frames takes almost 15 minutes -> this is one single minute of the video I want to analyse)

Post edited June 4, 2013 at 7:54 AM EST.

Post edited June 4, 2013 at 8:53 AM EST.

Compilation error

Tue, 04 Jun 2013 04:00:01 EST

Open Source Physics Forum: EJS Modeling
Thread: Compilation error
Author: Man Tol

Output message on all sample jar files producing compilation error message using even the new version (updated) ejs.

Post edited June 4, 2013 at 4:10 AM EST.

Xuggle library not found

Mon, 03 Jun 2013 13:46:16 EST

Open Source Physics Forum: EJS Modeling
Thread: Xuggle library not found
Author: Fabian Bühler

Dear all,

I've installed new most recent version of EJS and I've also installed Tracker.
Playing videos with Tracker works fine, so Xuggle is installed and working.
However, if I try to use the Video-element in EJS, there is an error message saying
"no xuggle -xuggler in java.library.path".

How can I add the correct path so that EJS is able to find Xuggle?

Thanks for any help.

Fabian

P.S.:
I'm using a Ubuntu 12.04-system.

Call for papers

Sat, 01 Jun 2013 19:26:13 EST

Open Source Physics Forum: EJS Modeling
Thread: Multimedia in Physics Teaching and Learning Meeting (Madrid, 11th-13th September)
Author: Luis de la Torre

Dear all,

The International Conference on Multimedia in Physics Teaching and Learning provides an annual forum to exchange information and ideas about the use of multimedia in physics teaching and learning. MPTL'18 is the eighteenth in the series of these workshops.

http://mptl18.dia.uned.es/mptl18

You are all invited to participate in this event, either by just assiting or by presenting a work.

For those interested in presenting a work, the deadline for the abstract submission (not longer than 400 words) is June 30.

The registration site will open next week. You can already take a look at the low prices of this conference in http://mptl18.dia.uned.es/mptl18/registration.html

Please find attached the official call for papers.

PS. Maybe this is not the best forum to publish this advertising but it seems the most active one. If the moderators think this message would fit better in any other (such as "General Comments", for example), please move this thread.

Post edited June 1, 2013 at 7:27 PM EST.

Post edited June 1, 2013 at 7:28 PM EST.

Distance Education and Online Learning

Sat, 01 Jun 2013 09:50:21 EST

Over the past dozen years the WebPhysics and Open Source Physics (OSP) projects have produced some of the most widely used computer-based curricular materials for the teaching of introductory and advanced physics courses. These materials are based on Java applets called Physlets and on new OSP programs and authoring tools. This session describes how we use these materials in the Davidson curriculum to motivate and engage students in computational physics modeling. In addition to learning to program, students are required to write and communicate, to develop their graphical design skills, and to apply mathematical reasoning to complex problems. We will demonstrate how physics can be taught by modeling, and how this approach helps to deepen the understanding of the underlying physical principles while supporting computational thinking.

Re: Re: Re: Augmented reality with remote cammera

Wed, 29 May 2013 10:42:35 EST

Open Source Physics Forum: EJS Modeling
Thread: Remote camera
Author: Diego Racero

Finally we've gotten EJS working with VLC as stream server.
The protocol that you must choose is HTTP and the encapsulation MJPEG, avoid the audio codec to assure only video streaming.

Re: Does Tracker Use (or require) Units?

Tue, 28 May 2013 13:59:43 EST

Open Source Physics Forum: Tracker
Thread: Using units in Tracker
Author: Douglas Brown

That's almost right. Tracker is unitless except for degrees/radians and also time is assumed to be in seconds. But mass and distance units are up to the user... Doug

Does Tracker Use (or require) Units?

Mon, 27 May 2013 12:29:34 EST

Open Source Physics Forum: Tracker
Thread: Using units in Tracker
Author: Todd Longfellow

Greetings, and thanks so such for a wonderful tool!

I am guessing that, outside of degrees or radians, Tracker is pretty much unitless. Is this correct?

Thank you for considering my question.

~todd

Post edited May 28, 2013 at 4:13 AM EST.

Re: Re: Screenshot Dialog

Wed, 22 May 2013 16:07:19 EST

Open Source Physics Forum: EJS Modeling
Thread: Screenshot Dialog
Author: Julia Branke

Dear Paco,

thank you so much, this is exactly what I needed!

_saveImage works for me

_view.saveImage does not (which explains, why I can not find if, if I look at the _view. functions offered in eclipse).

I will remember to look at the _functions in future.

Thank you,

Julia

Re: Screenshot Dialog

Wed, 22 May 2013 15:33:28 EST

Open Source Physics Forum: EJS Modeling
Thread: Screenshot Dialog
Author: Francisco Esquembre

Julia,

There is a method of the view called

  /**
   * Saves the image produced by a component to disk.
   * @param _filename the name of a file (either in disk or in memory). Null if the user must select a name.
   * @param _element the name of the view element to get the image from
   * @return true if the file was correctly saved
   */
  public boolean saveImage (String _filename, String _element);

You can invoke it as both _view.saveImage of _saveImage.
The syntax is:
_saveImage ("MyFilename.jpg","plottingFrame");

The "plottingFrame" String refers to an element in your view with that name.

Please, test this to see if it is what you need.

Paco

Re: any remote lab demo that i can access show to Singapore teachers?

Wed, 22 May 2013 06:08:44 EST

Open Source Physics Forum: OSP Programming
Thread: any remote lab demo that i can access and demo to Singapore teachers?
Author: Luis de la Torre

Hello lookang,

I have just created a user account in UNEDLabs (http://unedlabs.dia.uned.es) with access to one of our remote laboratories (the experiment with light in isotropic media for studying Snell's law).

However, I prefer not to post the login and password in a public forum.

Instead, write me an email to ldelatorre@dia.uned.es asking for the account details and I will tell you everything you need to know in order to access this remote lab :-)

Screenshot Dialog

Tue, 21 May 2013 10:19:13 EST

Open Source Physics Forum: EJS Modeling
Thread: Screenshot Dialog
Author: Julia Branke

In an ejs Simulation you can take a screenshot with right mouse click, screenshot (third from above in menue, not sure about what is really says in English) and then image.

My problem is (on OS X) that the dialog does not fit into the window that shows and it looks weird, unless you resize the dialog, but this is sort of not really obvious, that something is hidden.

I think the image that will be saved is just not scaled right into the dialog.

I wanted to offer a button in my simulation to save a screenshot and would be happy to have a dialog without any image in it.

In Eclipse I achieved this by making a function like the function saveImage out of SnapshotTool and commented out some lines (see end of post).

But if I package the simulation out of eclipse I get way bigger file sizes than out of ejs, and I have not figured out how to change this (any hints on this would also be appreciated) and so I would like to have the dialog without picture or with correctly displayed picture in ejs. A _view.saveImage function would be great.

I gave up the put my saveImage Function into ejs, because of all the imports I would need to do so. But maybe I will try again using the imports functionality in run options.

But I still would like the screenshot dialog to look neat.

Any help would be greatly appreciated.

    if((output==null)&&(filename==null)) {                                 // Select target file and scale
      JLabel label = new JLabel();
      label.setIcon(new ImageIcon(bi));
      /* This code is temporarily disabled because it doesn't work properly for all types of components
      */
//      JLabel labelScale = new JLabel(res.getString("SnapshotTool.Scale")); //$NON-NLS-1$
//      labelScale.setBorder(new javax.swing.border.EmptyBorder(0, 5, 0, 5));
      JTextField scaleField = new JTextField(Double.toString(scale));
//      JPanel scalePanel = new JPanel(new BorderLayout());
//      scalePanel.add(labelScale, BorderLayout.WEST);
//      scalePanel.add(scaleField, BorderLayout.CENTER);
//      JPanel panel = new JPanel(new BorderLayout());
//      panel.add(label, BorderLayout.CENTER);
//      panel.add(scalePanel, BorderLayout.SOUTH);
//chooser.setAccessory(panel);

any remote lab demo that i can access show to Singapore teachers?

Mon, 20 May 2013 22:19:41 EST

Open Source Physics Forum: OSP Programming
Thread: any remote lab demo that i can access and demo to Singapore teachers?
Author: lookang

hi professors,

is there any remote lab demo that i can access to show to Singapore teachers?
i tried to find some papers like
www.mdpi.com/1424-8220/13/2/2595/pdf
www.kirp.chtf.stuba.sk/pc09/data/papers/069.pdf?
but i don't know Math Lab server.

i can get a moodle only for now.
http://iwant2study.org/ejsapp/login/index.php

appreciate your help :)

NVT-Molecular Dynamics Model

Sun, 19 May 2013 18:33:32 EST

The NVT-Molecular Dynamics Model performs molecular dynamics simulations at constant temperature of 32, 108, 256 or 500 molecules interacting through the Lennard-Jones potential, in a wide range of densities and temperatures covering liquid, vapor and solid states. Thermodynamic properties, radial and speed distribution functions, velocity autocorrelation functions (vcf's) and their Fourier spectra, and mean square displacements (msd's) are calculated and displayed. Self-diffusion coefficients are worked out from the vcf's and msd's. Self space-time correlation functions (sstcf's) are estimated and compared with the Gaussian approximation. The 3D molecular motions can also be visualized. The motion equations are integrated by two methods, at user's choice: the damped-force with leap-frog Verlet's algorithm, and the "ad-hoc" rescaling with the velocity Verlet algorithm. The model allows to assess the role of the potential cut-off distance, the number of steps in equilibration runs, the time-step and the gap between time origins for vcf's, msd's and sstcf's.

The NVT-Molecular Dynamics Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Re: Re: Augmented reality with remote cammera

Sat, 18 May 2013 11:52:55 EST

Open Source Physics Forum: EJS Modeling
Thread: Remote camera
Author: Diego Racero

Andres, thank you for your help.

I haven't got an IP cammera, I'm was trying to use VLC, but a founf a problem because I don't know what codec I may use in order to get the image displayed.

Have you got any adavice.

Thanks in advance.

Instantaneous Frequency Stock Market Model

Fri, 17 May 2013 09:42:02 EST

The Instantaneous Frequency Stock Model estimates a stock's cyclical fluctuations over a three-day period to determine how fast the market is moving. The instantaneous frequency of an input signal is calculated by modeling an input function's most recent data points as a sin wave and performing a Fourier transform to derive the function's frequency. This model implements different velocity indicators on daily closing prices of a few common companies, and allows the user to compare values of the indicators at different times.

The Instantaneous Frequency model was developed by Matt Mohorn using the Easy Java Simulations (EJS) modeling tool. You can examine and modify the physical model for this simulation if you have Ejs installed by right-clicking within the plot and selecting "Open Ejs Model" from the pop-up menu.

Re: Augmented reality with remote cammera

Thu, 16 May 2013 08:05:45 EST

Open Source Physics Forum: EJS Modeling
Thread: Remote camera
Author: Andres Mejias

Diego,

you need an IP camera and, in the remore AR system (from the View 3D palette in EJS) , you must define the camera URL. For example, I use an Axis IP camera, and a valid URL could be:

http://127.0.0.1:8083/axis-cgi/mjpg/video.cgi

(change it with your IP address and port if you have one)

The URL depends on camera model and brand. If you don't have an IP camera, you need an streaming server in order to use an USB or local camera as an IP camera. For example, videoLan (VLC) is a good choice. This option is more complicated, because you use a camera, a computer and the streaming server. With an IP camera, you just need to connect it to the wired LAN.

Regards

Andres Mejias