STELLA tool

Note that uncertainties in the ignition conditions of the degenerate star leads to some irreducible diversity of the explosion kinetic energy, peak luminosity, nickel production for the same initial configuration. Modeling of light curves of SN la turns out to be a powerful tool to check the SN la explosion models (see recent calculations by multi-group radiation hydrocode STELLA [21]). 

To illustrate what Stella is and what it does, since it is somewhat less well known than equation solvers, spreadsheets, and symbolic computation tools, we present the simple case of an irreversible first-order reaction, A B. In Stella there are four icons that can be used to build models. These icons are called stocks, converters, flows, and connectors. We can use a stock to represent the concentration of A and another to represent the concentration of B. A flow then connects A to B. The flow has what appears to he a valve inserted in it. The opening of this valve can be conveniently set by means of a converter, the value of which can be thought of as the rate constant for the reaction. The connector from A to the flow allows the user to specify that the valve opening depends not only on the rate constant but also on the concentration of A. In our example helow we illustrate a first order reaction. The Diagram window for this simple reaction is shown in Figure 7. Besides the Diagram window there are three other windows available in Stella Equation Pad, Graph Pad, and... 

We have found that Stella is an effective tool to teach introductory kinetics and equilibrium concepts. Although it is true that all of this could be done in a spreadsheet or an equation solver, we believe that the presence of the Diagram window provides a strong visual connection between the model that is built and the mathematics behind the model. This example illustrates a realistic simulation of a real chemical phenomenon, of the sort recommended by Atkins. ... 

Keywords Boxer, collaboration, collaborative science, constructionism, constructivism, constructivist curriculum, constructivist educational strategies, creativity, databases, factual knowledge, graphs, kinematics, MBL tools, microcomputer-based laboratory, microcomputer-based labs, microworlds, modelling, physics, probe, science education, science misconceptions, science teaching, seismology, sensor, simulation, spreadsheets, STELLA, telecommunications, TERC, transducers... 

The solution of dynamic systems with software like STELLA and spreadsheets gives a broad range of students the tools with which they can understand complex systems. While not... 

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