Author Archives: mathscinotes

I Am Now A Grandpa

Posted on 31-October-2016 by mathscinotes

I am bursting with excitement right now. My youngest son and his wife now have a little girl. The baby arrived about 3 weeks early, but both mother and baby are doing fine. I could not be happier for their family.
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Posted in Personal | 5 Comments

Excel Data Table with More Than Two Input Variables

Posted on 30-October-2016 by mathscinotes

I am a big fan of Excel data tables, but I often struggle because they are designed to work with one or two input variables and a single output function. Many of calculations that I do have more than two input variables that I need to vary. These calculations also often have multiple output values. This post discusses how to create a data table with more than 3 input variables and more than one output variable. Continue reading →

Posted in Excel | 2 Comments

Tree Felling Miracle

Posted on 29-October-2016 by mathscinotes

I have seen a number of people fell trees onto homes and cars. Here is one case where two good-ol' boys dropped one successfully. Continue reading →

Posted in Humor | Comments Off on Tree Felling Miracle

What R-Value Is Good Enough?

Posted on 28-October-2016 by mathscinotes

I plan on retiring at my lake home in Northern Minnesota. The first step in my retirement preparations is building a large garage on my retirement property that will allow me to work on my various projects – I have not mentioned it before, but I love doing auto body work. I am currently building a garage similar to that shown in Figure 1. Because northern Minnesota is quite cold in the winter, I needed to insulate and heat this structure. This post will review some observations that I made as to the value of insulation and of using modern ventilation systems with heat recovery capability. Continue reading →

Posted in Construction | 4 Comments

Fighter Plane Statistics

Posted on 20-October-2016 by mathscinotes

So I prowled around the web and found a site that seemed to have some good information on the combat history of active jet fighters, including the F-16. I thought I would use this question as a vehicle for sharpening my Power Query and Excel web scraping skills by making comparison table between the active duty fighter jets. Continue reading →

Posted in History Through Spreadsheets, Military History | Comments Off on Fighter Plane Statistics

Using Excel's Icon Sets for Testing Equality -- Ugh

Posted on 7-October-2016 by mathscinotes

I use Excel everyday, but that does not mean that I have used every feature. Yesterday, I was asked to prepare an analysis for our marketing group of the maximum possible distances that over which a customer can be served using various types of fiber optic communication systems – we call this parameter "reach". During this analysis, I saw what I thought was an ideal opportunity to use Excel's icon sets for the first time (Figure 1). Continue reading →

Posted in Excel | 7 Comments

Battery Room Ventilation Math

Posted on 4-October-2016 by mathscinotes

In this post, I will be looking at how these ventilation calculations are performed. My focus here is on standard wet-cell batteries, which simply release any gases generated during charging. Other battery types, like Absorbed Glass Mat (AGM), will attempt to recombine the H2 and O2 released during charging. The AGM battery's internal gas recombination will reduce the amount of H2 released by these batteries – example shown here. I will compare the output of my model to those generated by a number of web-based and textbook sources. The results are in good agreement. Continue reading →

Posted in Batteries | 1 Comment

Effective R Value of Common Wall Construction Methods

Posted on 1-October-2016 by mathscinotes

Because the winters are hard in this part of the country, I have become interested in the insulation value of different types of wall construction. My contractor has his preferred approach, and I am curious as to how it compares with other framing methods.

In this post, I will put together a simple model for computing the R-value of different types of wall construction. This analysis will provide me a quantitative basis for understanding which methods are the most economically sound. Continue reading →

Posted in Construction | 1 Comment

Effect of Wire Length on Surge Protector Let-Through Voltage

Posted on 28-September-2016 by mathscinotes

While reading about how these units worked, I noticed that the amount of surge voltage they let pass (called let-through voltage) is a function of the hookup wire length. The units are tested with a hookup length of 6 inches, and the user is warned that the let-through voltage increased by ~20 V per inch of additional wire. I became curious about the origin of this rule of thumb. In this post, I will show you where this rule of thumb comes from. Continue reading →

Posted in Electronics | Comments Off on Effect of Wire Length on Surge Protector Let-Through Voltage

Video of Wild Cat in Northern Minnesota

Posted on 19-September-2016 by mathscinotes

Like me, a number of my coworkers have cabins in Northern Minnesota and most of us have cameras that record activity on our properties. A coworker came in the other day with this video that shows a wild cat going by one of his cameras. I am not sure what kind of cat it is – probably a lynx. This site is not far from the Canadian border. Maybe one of you out there can identify it? Continue reading →

Posted in Cabin, Personal | Comments Off on Video of Wild Cat in Northern Minnesota