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Author Archives: mathscinotes
I just finished watching a series of videos on the Guadalcanal Campaign by Drachinifel, whose work is superb (Figure 2). The marines derisively referred to this campaign as Operation Shoestring because of the resource limitations. Things were no better for the sailors. Unlike many WW2 island campaigns, more sailors died in the battles than ground troops (link). The Allies, and in particular the US Navy (USN), had to learn the hard way that the Imperial Japanese Navy (IJN) was a force that deserved respect. Many Allied ships were sunk while learning this lesson. Continue reading
My reading and watching lectures on Mahan have motivated me to look at how the US Navy grew and shrank over the years. Fortunately, the Naval History and Heritage Command (NHHC) have an excellent page on the size of the US Navy over time. Unfortunately, the data is scattered throughout the page and it must be scrapped so that I can consolidate and graph it. This post is about using Power Query to scrape the data from the page and generate a graph in Excel of the number of active ships in the US Navy over time. Continue reading
Two weeks ago, the grass around my garage looked pretty scraggly and weed-infested, so I decided it was time for fertilizer and weed-killer. I am not very knowledgeable about lawns and lawn care, so I decided to research online. This research is summarized in this post. Yes, it was time for some fertilizer and weed-killer. Continue reading
During a major storm two weeks ago with 80 mile per hour winds (129 kph) and heavy rain, a lightning strike near my garage destroyed two TVs, a power adapter for my robot lawnmowers, a wireless router, two data switches, and my furnace's propane tank regulator and copper feedline. As an illustration of the damage, Figure 1 shows the residue left from my mower power adapter exploding. The light region inside the smudge is from my fingers wiping across the smudge to see how thick the film was. The film was removed using mineral spirits. A small burn mark is all that remains. Continue reading
I use Python or R for my large-scale data work, but I do find Excel a very powerful ad hoc data analysis tool, particularly with some of the new functions that use spillable ranges. Today, I was given a large table of Engineering Change Orders (ECOs) and a comma-separated list of the documents each ECO affected (very abbreviated form shown in Figure 1). Continue reading
Quote of the Day Great things are not done by impulse, but by a series of small things brought together. — Vincent van Gogh Introduction I recently went into a home center and was shocked to see a 2‑in x … Continue reading
A number of people have asked questions about the process we used to design and build our cabin in northern Minnesota (Figure 1), a build that I have discussed in other posts (link, link). The questions center on the tools we used, what the build process was like, and things to watch for. The following post examines our design and build process from the standpoint of what went well and not so well. Continue reading
I recently had a situation where I needed to correct a number of date/time values because they did not take into account Daylight Saving Time (DST). To be specific, some transactions from China were recorded assuming a fixed time offset with respect to US Central Standard Time. Because of DST, this is not always the case. My customer only works in Excel, so the work was done in Excel. Continue reading
I was watching a documentary on the Battle Off Samar on my favorite Youtube naval channel called Drachinifel. During this show, Drachinifel stated that the battleship Yamato displaced more tonnage than the entire Task Group 77.4.3 (call sign Taffy 3) defense force. I found this a remarkable statement and one that I could verify using a little bit of web scraping. Because one of the students I tutor use R, I thought this would be a good exercise to implement using R and Rmarkdown (a great report generation tool). Continue reading