Author Archives: dougaj4

The hole through the middle of the Earth – moved to the Equator

Posted on 02/08/2010 by dougaj4

Previous posts in this series assumed that the hole went from pole to pole, and ignored such complications as tidal effects and wobbles of the axis of rotation.  In this post we will examine the effect of moving the hole … Continue reading →

Posted in Differential Equations, Excel, Maths, Newton, UDFs, VBA | Tagged , , , , , | 2 Comments

Code Generator

Posted on 22/07/2010 by dougaj4

One of the difficulties with Excel routines to solve differential equations, or do numerical integration, is that the equations to be solved must either be coded as VBA functions (which is time consuming), or solved using the evaluate function (which … Continue reading →

Posted in Excel, VBA | Tagged , , | 1 Comment

Lateral pile analyis with PY curves …

Posted on 17/07/2010 by dougaj4

… and non-linear pile properties. In previous posts I have presented Excel User Defined Functions (UDFs) to analyse a laterally loaded pile, generate soil PY Curves based on the recommendations in the COM624 Manual, and determine the flexural stiffness of cracked … Continue reading →

Posted in Concrete, Excel, Geotechnical Engineering, Newton, UDFs, VBA | Tagged , , , , , | 17 Comments

Arches, anagrams and plagiarism

Posted on 14/07/2010 by dougaj4

A previous post discussed Robert Hooke’s solution for the optimum shape of an ach structure standing under its own weight: “Ut pendet continuum flexile, sic stabit contiguum rigidum inversum” which translates as: “As hangs the flexible line, so but inverted will … Continue reading →

Posted in Arch structures, Newton | Tagged , , , | 3 Comments

The hole through the middle of the Earth – revised transit time

Posted on 08/07/2010 by dougaj4

In the previous post in this series I produced a table of acceleration due to gravity against depth from surface, based on the four layers of the Earth (Crust, Mantle, Outer Core, Inner Core), assuming a constant density for each layer.  … Continue reading →

Posted in Differential Equations, Excel, Newton, UDFs, VBA | Tagged , , , , | 3 Comments