Author Archives: mathscinotes

Another Excel TEXTJOIN Example

Posted on 28-September-2019 by mathscinotes

I have been analyzing seemingly random fuse failures in different products. The failing fuse is similar to the unit shown in Figure 1. My analysis has shown that the fuses are failing because of damage they are sustaining during the manufacturing process. In my analysis report, I was asked to list each product that experienced a fuse failure and to list how many days each product was in service before the fuse failure occurred. Continue reading →

 
Posted in Excel | 1 Comment

Battleship Classes and Throw Weights

Posted on 26-July-2019 by mathscinotes

I just finished reading The Battle of Surigao Strait by Anthony Tully, a battle that saw the final clash of battleships. For a battleship aficionado, the climax of the fight was the contest between two Japanese battleships and six US battleships, where five of the six US battleships had been sunk or heavily damaged during the Pearl Harbor attack – only the USS Mississippi had escaped the carnage of Pearl Harbor. These were old battleships (Table 1) with two having been commissioned during WW1 and the rest shortly after the WW1 ended. Continue reading →

 
Posted in History Through Spreadsheets, Military History, Naval History | 11 Comments

Everest Climbers With No Supplemental Oxygen

Posted on 21-June-2019 by mathscinotes

I recently have seen pictures on the news of a line of people preparing to summit Mount Everest (Figure 1), which got me thinking about the difficulty of waiting in line under low-pressure conditions.The vast majority of the people who climb Everest use supplemental oxygen. The air pressure at the summit of Everest is about 0.3 atmosphere, which is not enough to support human life for an extended period of time. But a relatively small number of people have climbed Everest with No Supplemental Oxygen (NSO). In this post, I will look at this very select group of people. Continue reading →

 
Posted in History Through Spreadsheets | Leave a comment

My Robot Lawn Mowers

Posted on 14-June-2019 by mathscinotes

I am working today in my garage office at my cabin in northern Minnesota. From the office window, I can see a Worx Landroid robot mowing the lawn (Figure 1). I installed two of these mowers  (one for garage and one for cabin) because I am not regularly at the cabin and wanted to ensure the lawn was mowed even when I could not be there. Continue reading →

 
Posted in Cabin | Leave a comment

US Dairy Industry Stats

Posted on 3-June-2019 by mathscinotes

Early in my life, I spent quite a bit of time around cows on small farms with about 160 to 200 acres of land, and 40 to 50 cows. I never saw a corporate farm. Three years ago, I spent quite a bit of time in Iowa working on a number of fiber optic deployments in rural areas populated with a large number of dairy operations. While performing fiber installation inspections, I noticed that many of the old farmhouses were occupied by renters and the land was being farmed by corporations. As I looked around both Iowa and Minnesota, I realized that the number of dairy farms is dropping fast (Figure 1).  Continue reading →

 
Posted in Farming | 1 Comment

Using Excel to Convert a Number List to Dashed String of Ranges

Posted on 18-May-2019 by mathscinotes

While working on a test report for an aircraft manufacturer this week, I needed to convert a large number of number lists to strings of dashed ranges. For example, suppose you are given a list {1, 2, 3, 5, 6, 7, 8, 10}. Converting this list to a dashed set of ranges means generating the string "1-3, 5, 6-8, 10." Figure 1 shows another example with an optional prefix added to each number. Continue reading →

 
Posted in Excel | 1 Comment

US Iron and Aluminum Mining During WW2

Posted on 4-May-2019 by mathscinotes

My vacation/retirement cabin is in the iron mining region of Minnesota. The rock throughout the area shows the reddish hue of iron. I recently heard some old-timers talking about how the intensity of mining operations during WW2 took the last of the high-grade iron ore (hematite –Figure 1) and left only low-grade ore (taconite). This comment made me curious about mining during WW2. Continue reading →

 
Posted in History Through Spreadsheets | 2 Comments

Estimating Exponential Time Constants

Posted on 2-May-2019 by mathscinotes

I have been presented with a large amount of experimental data from which I need to determine many exponential time constants. There are so many time constants to calculate that I need to automate the process. Continue reading →

 
Posted in General Mathematics | Leave a comment

Determining RMS Acceleration for a Vibration Acceleration Spectral Density

Posted on 27-April-2019 by mathscinotes

I was asked last week to write a vibration test plan for a mobile electronic product. I am used to writing vibration test plans that follow canned procedures in standards like MIL-STD-810F or SAE J1455, but this case is different because the customer has specified a non‑standard random vibration acceleration profile, which is also called a Power Spectral Density (PSD). I need to determine the RMS g level for this profile. This post shows how I go about this calculation. I am not going to showing the customer's vibration PSD because it is proprietary. Instead, I will use a well‑known US Navy vibration PSD as a computation example (Figure 1). Continue reading →

 
Posted in General Mathematics | Leave a comment

Let's Grow Some Oats

Posted on 21-April-2019 by mathscinotes

I am going to grow and process some oats this year. This is a project that I have been interested in doing for a while because one of my sons is now in the oat business and he has shown some interest in working through the entire oat processing cycle. As a boy, I used to mill oats on the family farm, but I remember very little of that time. Continue reading →

 
Posted in Excel, General Mathematics | Leave a comment