http://www.compadre.org/OSP/ Open Source Physics's Modeling Features en-US Copyright 2013, ComPADRE.org osp@compadre.org (Managing Editor) Sun, 19 May 2013 17:58:18 EST http://blogs.law.harvard.edu/tech/rss http://www.compadre.org/OSP/services/images/LogoSmallOSP.gif http://www.compadre.org/OSP/ 125 35 The Gray-Scott Reaction Diffusion Model displays the spatial concentration of chemical species U and V under the influence of the reaction U+2V->3V and V->P. The simulation models this reaction in an open system with a constant addition of U and removal of V due to a flow. Combining this autocatalytic process with diffusion results in pattern formation that has a surprising variety of spatiotemporal patterns when starting in the initial state U=1 and V=0 except for a square grid at the center where U=1/2 and V=1/4. http://www.compadre.org/OSP/items/detail.cfm?ID=12017 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=12017&DocID=2872 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=12017 Sat, 26 May 2012 00:00:00 EST The Boltzmann Distribution From A Microcanonical Ensemble Model allows students and instructors to explore why the Boltzmann distribution has its characteristic exponential shape. In this model, particles have only one degree of freedom–the energy to move in one dimension. http://www.compadre.org/OSP/items/detail.cfm?ID=11563 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11563&DocID=2483 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=11563 Sat, 03 Dec 2011 00:00:00 EST The Simulated Annealing Method for the Traveling Salesman Model demonstrates the use of the "simulated annealing algorithm" to attempt to solve the "travelling salesman" problem. A text file containing longitude and latitude data for 120 cities in the US and southern Canada is loaded when this program begins. http://www.compadre.org/OSP/items/detail.cfm?ID=11538 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11538&DocID=2459 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=11538 Wed, 30 Nov 2011 00:00:00 EST The 3-D Hydrogen Atom Probability Densitites model simulates the probability density of the first few (n = 1, 2, and 3, and associated l and m values) energy eigenstates for the Hydrogen atom (the Coulomb potential). The main window shows the energy level diagram for the solutions to the Coulomb potential in 3D. http://www.compadre.org/OSP/items/detail.cfm?ID=10532 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=10532&DocID=2038 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=10532 Sun, 12 Dec 2010 00:00:00 EST The EJS Phases of Moon model displays the the appearance of Moon and how it changes depending on the position of Moon relative to Earth and Sun. The main window shows Earth (at the center). By using the Options Menu the Moon View window shows the appearance of Moon as seen from Earth when Moon is in the position shown in the main window. http://www.compadre.org/OSP/items/detail.cfm?ID=9308 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9308&DocID=1247 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=9308 Thu, 11 Nov 2010 00:00:00 EST The Ejs QM Eigenstate Superposition Demo model displays the time dependence of a variety of superpositions of energy eigenfunctions for the infinite square well and harmonic oscillator potentials. One of the eleven pre-set superpositions can be selected via a drop-down menu with the resulting wave function shown in phase-as-color representation. http://www.compadre.org/OSP/items/detail.cfm?ID=8195 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=8195&DocID=863 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=8195 Thu, 11 Nov 2010 00:00:00 EST The Exoplanet Detection: Transit Method model simulates the detection of exoplanets by using the transit method. In this method, the light curve from a star, and how it changes over time due to exoplanet transits, is observed and then analyzed. When the exoplanet passes in front of the star (transits), it blocks part of the starlight. This decrease in starlight is shown on the graph. http://www.compadre.org/OSP/items/detail.cfm?ID=10156 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=10156&DocID=1734 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=10156 Tue, 29 Jun 2010 00:00:00 EST The EJS Newton's Mountain model illustrates the motion of a projectile launched from the top of a VERY tall mountain on Earth. The diagram shown in the simulation is taken from Newton's A Treatise on the System of the World, which he wrote after the Principia. Newton concluded that a projectile launched horizontally with sufficient speed would orbit Earth rather than crashing to Earth's surface. http://www.compadre.org/OSP/items/detail.cfm?ID=9391 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=9391&DocID=1299 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=9391 Wed, 26 Aug 2009 00:00:00 EST The Ejs Great Circles model displays the frictionless motion of a particle that is constrained to follow the surface of a perfect sphere. The sphere rotates underneath the particle, but since there is no friction, and the sphere is perfectly spherical, the motion of the particle is not influenced by the sphere. http://www.compadre.org/OSP/items/detail.cfm?ID=8483 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=8483&DocID=945 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=8483 Mon, 19 Jan 2009 00:00:00 EST The Ejs Platform on Two Rotating Cylinders model displays the model of a platform resting on two equal cylinders are rotating with opposite angular velocities. There is kinetic friction between each cylinder and the platform. The separation between the cylinders and the coefficient of kinetic friction can be changed via textboxes. http://www.compadre.org/OSP/items/detail.cfm?ID=8156 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=8156&DocID=829 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=8156 Thu, 09 Oct 2008 00:00:00 EST The EJS Normal Modes on a Loaded String model displays the motion of a light string under tension between two fixed points. The string is also loaded with N masses located at regular intervals. The number of masses on the string can be changed via textboxes. http://www.compadre.org/OSP/items/detail.cfm?ID=8130 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=8130&DocID=820 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=8130 Thu, 02 Oct 2008 00:00:00 EST The EJS Orbiting Mass on a Cone 3D model displays the frictionless dynamics of a mass constrained to orbit on the inside of a cone. The simulation displays the motion of the masses as well as the effective potential energy. The cone angle and the total energy and the initial radial position of the mass can be changed. http://www.compadre.org/OSP/items/detail.cfm?ID=7608 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=7608&DocID=607 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=7608 Thu, 10 Jul 2008 00:00:00 EST The EJS Ball in a Wedge model displays a ball confined to move between two walls that form a wedge shape. The ball undergoes elastic collisions with the walls of the wedge. http://www.compadre.org/OSP/items/detail.cfm?ID=7575 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=7575&DocID=595 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=7575 Sat, 05 Jul 2008 00:00:00 EST The much studied Fermi-Pasta-Ulam problem was one of the first computational experiments and it still fascinates computational physicists. This EJS simulation shows the time evolution of the mode energies as reported in the original paper. http://www.compadre.org/OSP/items/detail.cfm?ID=6891 http://www.compadre.org/Repository/document/ServeFile.cfm?ID=6891&DocID=309 http://www.compadre.org/OSP/bulletinboard/Thread.cfm?ID=6891 Fri, 30 May 2008 00:00:00 EST