Programs  for  Download  from  Brantacan

This web-site includes computer programs which simulate engineering principles and scientific principles.  This page gathers them all together and explains what each one does.

In most of the programs the keys "<", ">", "-" and "+" are used to control variables.  On a UK keyboard the corresponding unshifted characters are recognised by the programs, so the shift key is not required.  In some cases, the program recognises key-presses after a short delay while it completes a cycle.

The programs can be run in their current location, or saved to a file.

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ALIAS.EXE     This program simulates two moving grids of lines, which are illuminated regularly by a stroboscopic lamp.  Left to itself, the program will change the speed of movement in equal increments, but the f and s keys can be used to over-ride the program.  Aliasing of the coarse grid and the fine grid are seen to occur at different speeds, demonstrating the relationship between sampling rate and event frequency.  A numerical value shows the speed of movement in arbitrary units.

 

ALIASES.EXE     This program is similar to the previous one.

 

ALIASING.EXE     This program demonstrates both visual aliasing and physical aliasing.  The green curve is an input signal.  The white dots show the effect of drawing samples on an oscilloscope screen.    At certain signal frequencies the eye-brain combination may try to create patterns which give a false impression of what is happening.  The red lines show samples which have been joined up to avoid visual aliasing.  The effects of physical aliasing appear when the signal is too fast for the sampling.  The q key enables quitting the program.

 

ARCHLOAD.EXE     This program simulates the passage of loads across a concrete arch.  The speed and size of the loads are chosen randomly, the size being indicated by the length of the vertical line.  The white curve shows the position of the line of thrust.

 

ARCHSTIF.EXE     This program is similar to the previous one, except that a deck stiffened arch is depicted.

 

BEAMLOAD.EXE     Loads pass randomly over a simple beam.  The program shows the behaviour of the bending moment.

 

BRANCAT.EXE     Calculates caternary arches with different ratios of rise to span and thickness of voussoirs.

 

BRANTAC.EXE     Calulates data for building a model suspension bridge.

 

FIB1NB.EXE    Simulation of growth of a sunflower.

 

FIBONACCI     Larry Albertelli has kindly supplied two good pictures of Fibonacci structure in flowers.  They can be downloaded here, a PDF and a Postscript file.

 

GSF.EXE    In this simulation, radial lines are set at equally spaced angles around a centre.  For each picture the angle is chosen randomly.  The lengths of the lines fall exponentially going around the circle.  In the second part of the demonstration the angle is fixed at the "golden angle", about 222.492 °, and the space is filled more efficiently than in any of the other examples.  

 

MULTSINE.EXE     A set of sine waves with random frequencies and phases passes by.  The program shows how the amplitude can vary from small to large values, and that very small or very large values are relatively rare.  The program can be restarted with a new set of random variables, using the r key.  

 

PHASORS.EXE     A simulation of some of the properties of phasors in AC theory.

 

PHASORSB.EXE     Another version of the same program.

 

RAINBOW.EXE     This program simulates the passage of a laser beam through a spherical drop of water, with one reflection, revealing the minimum deflection angle which is responsible for the intensity peak near that angle.

 

SIDEWINDER.EXE    A simulation of the behaviour of a side-winding snake.

 

SNAKING.EXE     A simulation of the behaviour of the ventral scales of a snake in linear motion.

 

STMOLS.EXE     A crude simulation of the interface between a liquid and a gas.  On the left the boundary is sharp.  On the right it is fuzzy, showing the region of reduced density which results in surface tension.

 

TWAVES.EXE     A simulation of travelling waves, and the way they combine to make standing waves when they are reflected.

 

TWOPEND.EXE     A simulation of two coupled pendulum, showing the two normal modes and the result of mixing the two modes.

 

TWOSLITS.EXE    Simulation of the amplitude and intensity produced by two slits.  The one-slit pattern can be made by setting width and separation equal.   Suitable starting values are 100 and 200.

 

VIBES.EXE     Simulation of the oscillation of a suspension bridge in flexure and torsion.

 

VIBES3.EXE     Simulation of the lowest normal modes of a stretched cable and a hanging cable.

 

VIPSWIM.EXE    Simulation of the motion of a swimming snake.

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