New uCOMP collection resources

Computational Science Education Reference Desk (CSERD)

Sat, 05 Nov 2011 11:29:52 EST

This is the node of the National Science Digital Library (NSDL) that is dedicated to all resources for computational science education.

Rectangular Well Model

Sat, 05 Nov 2011 11:26:36 EST

The Rectangular Well model displays the 2D energy eigenstates of a particle trapped in a very deep two-dimensional rectangular well. Because the Schrödinger equation for this system is separable into one-dimensional infinite square well Hamiltonians, the solution can be expressed as a product of the two one-dimensional solutions. Uses can select the quantum numbers and the spatial dimension of the well. This model is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_qm_RectangularWell.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 plot and selecting “Open Ejs Model” from the pop-up menu item.

Three State Nuclear Decay Model

Sat, 05 Nov 2011 11:20:05 EST

The Three State Nuclear Decay model extends the Two State Nuclear Decay model (also available through OSP and ComPADRE) to simulate the radioactive decay of atomic nuclei in which the parent nucleus first decays into an intermediate state before decaying into a stable state. Although the decay of both the parent and intermediate nucleus (radionuclides) is spontaneous and unpredictable, the probability of decay of each radionuclide is constant and is usually known. The model displays a color-coded sample with N1 parent nuclides, N2 intermediate state nuclides, and N3 stable state nuclides. Users can set the initial numbers N1 and N2, the decay the decay constants k1 and k2, and the time interval between measurements Δt before the simulation is run. The simulation counts the number of decay events and stops when all nuclides are in the stable state. Check boxes display a plot and a table showing the time evolution of each state as well as the number of decay events in each time interval. The data plot allows users to compare the data generated by the random decay model with a differential equation-based model. The Three State Nuclear Decay 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 ejs_nuclear_ThreeStateNuclearDecay.jar file will run the program if Java is installed.

Computational Physics for Upper Level Courses Topical Conference

Wed, 28 Sep 2011 17:36:25 EST

These conference proceedings provide the presentations, activities, and outcomes of the 2007 AAPT Topical Conference on Computational Physics. This conference explored the tools, common practices, and pedagogy used in physics departments to instruct students in computational methods and the use of computer-based resources. The materials available include a summary and outcomes of the conference, invited talks, and some of the contributed posters.

How to calculate the vibration of an inhomogeneous string using MATLAB programs

Wed, 28 Sep 2011 17:35:54 EST

This paper presents a solution to the dynamics of a vibrating inhomogeneous string by the method of separation of variables in x and t. The solution consists in transforming the differential equation in x into an integral equation, which is subsequently solved by means of a spectral method. As an extension of a paper in the American Journal of Physics, this material describes and makes available the MATLAB programs required for the spectral calculations.

Solar Photon Random Walk

Wed, 28 Sep 2011 17:35:15 EST

The Solar Photon Random Walk Model simulates the path of photons in radiative transport as they escape from the Sun. Photons do not travel in a straight line, but rather collide with larger particles and get redirected. This simulation models that process using a random walk in polar coordinates. The random walk parameters are adjustable to match different models of the structure of the sun, or the user can input their own values. The Solar Photon Random Walk Model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_comp_phys_photon_random_walk.jar file will run the program if Java is installed.

Cyclotron in 3D Model

Wed, 28 Sep 2011 17:34:45 EST

This simulation illustrates the operation of a cyclotron, showing a charged particle moving through combined magnetic and electric fields. The particle, started near the center of the cyclotron, accelerates when passing through the gap between the electric electrodes and is turned by a perpendicular magnetic field. The geometry of the cyclotron, the magnitude of the electric and magnetic fields, and the properties of the charge are all adjustable. This page includes links to information on the operation of cyclotrons.

Software Carpentry

Wed, 28 Sep 2011 17:34:00 EST

This web site is created to help scientists and engineers learn the concepts, skills, and tools needed to use and build software more productively. Topics range from shell and scripting languages to web programming and software engineering. Instructional materials include video lectures and slides to practice exercises.

General Purpose Math Visualizer Package

Sun, 19 Jun 2011 09:01:47 EST

The General Purpose Math Visualizer Package performs mathematical tasks that are commonly encountered in physics: plotting, animating, numerically differentiating and integrating, and solving systems of coupled algebraic equations. The General Purpose Math Visualizer Package was developed using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_GeneralPurposeMath.jar file will run the program if Java is installed. An alternate version (ejs_GeneralPurposeMath_lowres.jar) is also included below that should fit on the screen more nicely when using a display set to a low resolution.

EJS CSM Textbook Chapter 7: Random Processes

Sun, 12 Jun 2011 14:33:38 EST

This book chapter introduces Random processes in the context of several simple physical systems, including random walks on a lattice, polymers, and diffusion controlled chemical reactions. The generation of random number sequences also is discussed.

Colorado State University: Mathematical Modeling Applets

Sun, 12 Jun 2011 14:29:47 EST

This is a collection of 13 Java applets relating to computational mathematics. Each applet demonstrates a particular mathematical model of a physical system in an interactive format. Models include exponential growth, logistic growth, best quadratic, least squares circle, transient heat flow, and flow in a homogeneous porous medium. These materials were developed to accompany a course on high performance computing, but would also serve to supplement any course that uses scientific visualization tools for viewing large data sets.

Driven Wave Machine Model

Wed, 16 Feb 2011 16:22:28 EST

The Driven Wave Machine model simulates a wave machine driven by a sinusoidal oscillator. The machine consists of horizontal bars welded to a torsion rod that is perpendicular to the bars. The simulation allows the user to change the number of bars, the drive frequency, and the boundary conditions. The simulation also allows the user to change the lengths of the bars, thereby simulating the effect of a wave propagating in a non-uniform medium. The Driven Wave Machine model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_mech_osc_chains_DrivenWaveMachine.jar file will run the program if Java is installed.

Driven Mass and Spring Mesh Model

Wed, 16 Feb 2011 16:22:00 EST

The Driven Mass and Spring Mesh model displays the dynamics of a 2D array of masses coupled by springs and driven by a sinusoidal force. The model shows a time-dependent animation of the displacement or each mass. The driving force can be applied at a single point (shown in red) or uniformly at all mesh points and the drive frequency f and amplitude A can be set as well as a damping coefficient b. As the frequency is varied the mesh vibrates strongly (resonates) at some frequencies and very little at others. These resonances have patterns that were first studied by Ernst Chladni and this simulation is designed to investigate these patterns using an idealized mass and spring model. In order to find the resonances, it is useful to plot the mechanical energy as a function of frequency f after the system reaches its oscillatory steady state. A resonance scan option shows this plot. The Driven Mass and Spring Mesh model is a supplemental simulation for the article "Chladni Patterns on Drumheads: A Physics of Music Experiment" by Randy Worland in The Physics Teacher 49(1), 24-27 (2011) and has been approved by the authors and The Physics Teacher editor. The 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 ejs_mech_DrivenMassAndSpringMesh.jar file will run the program if Java is installed.

EJS Eclipse workspace

Wed, 16 Feb 2011 16:21:29 EST

The EJS Eclipse Workspace contains a ready to use Eclipse workspace with source code for the EJS modeling and authoring tool. Unzip this workspace and open it from within Eclipse to compile EJS. The EJS Eclipse workspace is for professional programmers who wish to modify or enhance EJS. Use the ready-to-run (compiled) distribution of EJS to create and modify EJS simulations.

Orbits Within Spherical Galaxies Model

Wed, 16 Feb 2011 16:20:31 EST

The Orbits Within Spherical Galaxies model displays the two-dimensional trajectories of particles (stars) within a galaxy having a spherically symmetric mass distribution that heuristically approximates the distributions found in galaxies and bulges. The model uses a mass density proposed by Walter Dehnen to describe spatial distributions that vary as r^-4 and r^-g in galactic envelopes and cores where g is an adjustable power-law parameter. Units are chosen such that a typical galaxy has total mass M=1 and that the gravitational constant G=1. The Orbits Within Spherical Galaxies 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 ejs_mech_orbits_OrbitsWithinSphericalGalaxies.jar file will run the program if Java is installed.

Two State Nuclear Decay Model

Wed, 16 Feb 2011 16:19:31 EST

The Two State Nuclear Decay model simulates the radioactive decay of atomic nuclei into other nuclei. In this model, the resultant nuclei are stable and there are no intermediate decay states. Although the decay of a radioactive nucleus (radionuclide) is spontaneous and the time of its decay cannot be predicted, the probability of its decay k is constant and is usually known. The model displays a radioactive sample with N nuclides. Radioactive nuclides are color-coded red and decayed nuclides are color-coded blue. Users can set the number of nuclides N, the decay constant k, and the time interval between measurements before the simulation is run. The simulation counts the number of decay events and stops when there are no radionuclides remaining. The Two State Nuclear Decay 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 ejs_nuclear_TwoStateNuclearDecay.jar file will run the program if Java is installed.

Confined Hard Disk System Model

Wed, 16 Feb 2011 16:19:02 EST

The Confined Hard Disk System is an idealized statistical mechanics model that simulates a two-dimensional system of hard disks confined to a box with a constant temperature thermal reservoir at one end and a movable piston at the other. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The model computes and plots the time evolution of the kinetic energy K per particle, the pressure P, and the volume V. The model also displays histograms and mean values of these quantities. The Confined Hard Disk System was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_hd_ConfinedHardDiskSystem.jar file will run the program if Java is installed.

Confined Lennard-Jones System Model

Wed, 16 Feb 2011 16:18:15 EST

The Confined Lennard-Jones System is an idealized statistical mechanics model that simulates a two-dimensional system of particles confined to a box with a constant temperature thermal reservoir at one end and a movable piston at the other. Particles in this model have unit mass and interact through pairwise Lennard-Jones forces and hard-wall contact forces. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The model computes and plots the evolution of the total energy E, the kinetic energy per particle K, the pressure P, and the volume V. The model also displays histograms and mean values of these quantities. The Confined Lennard-Jones System was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_md_ConfinedLennardJonesSystem.jar file will run the program if Java is installed.

Hertzsprung–Russell (H-R) Diagrams

Wed, 16 Feb 2011 16:17:42 EST

The Hertzsprung–Russell (H-R) Diagrams model simulates Hertzsprung–Russell (HR or H-R) diagram for groups of stars. The diagram is a scatter plot of steller luminosity vs. stellar temperature. The luminosity of stars is proportional to the star's radius squared and its temperature to the fourth power, and for Main Sequence stars, their luminosity is also proportional to their mass to the 3.5 power. Since the range of stellar luminosities and stellar temperatures is so large, the plot uses a log-log scale. The diagram is a way to understand stellar evolution. The HR diagram shows nearby stars, bright stars, and a user-defined star. One can also show the blackbody radiation curve and the user-defined star. The radius of the user-defined star (in Rsun) and the temperature of the user-defined star in Kelvin (5780 K is Tsun) can be changed.

Stellar Blackbody Radiation Curves

Wed, 16 Feb 2011 16:17:04 EST

Stellar Blackbody Radiation Curves model simulates the blackbody radiation curve of stars and how this leads to the observed color and luminosity of the star. If a star can be treated as a blackbody, the blackbody radiation curve of the star, the power density per area (or intensity) per wavelength (energy/time/volume) vs wavelength, is dependent on the star's temperature (spectral class). In the simulation, the star is shown along with its luminosity and spectral class. In separate graph, the blackbody radiation curve, the visible part of the spectrum, and the integrated stellar surface intensity (integrating the blackbody curve over all wavelengths) are shown. In another window the HR diagram can be shown indicating the current star's parameters. The radius of the star (in Rsun) and the temperature of the star in Kelvin (5780 K is Tsun) can be changed.