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Author Archives: mathscinotes
Retired Hurricane Name Statistics
I was reading an article that stated that names of Hurricane Harvey and Irma could be the eighth pair of back-to-back hurricane whose names have been retired since the 1954. I have never thought about which hurricane names have been retired, so I started to search around the web. As usual, the Wikipedia provided an excellent data source. Continue reading
Posted in History Through Spreadsheets
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Examples of Lake Clarity Variation Over Time
I am having my cabin built on a small lake in northern Minnesota. At the same time that the cabin is being built, a friend is in the process of locating an an existing cabin for purchase on a nearby lake – there are dozens of lakes within a few miles of my building site. He has been asking questions about the clarity of the water in these lakes. Fortunately, the state of Minnesota has an excellent web page with all sorts of technical data on lake water, including clarity measurements. Professional lake monitors are also used. On a regular basis, they gather technical information on the lakes: chemistry, fish populations, presence of invasive species, etc. The lake water clarity data historically has been measured using a Secchi disk (Figure 1) and volunteer lake monitors. In recent years, satellites have been tasked with clarity monitoring as well. So there are now two sources of lake clarity information that can be used to cross-check one another. Continue reading
Posted in Excel, General Science
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Hurricanes and Typhoons Ranked By Air Pressure
I was watching the weather reports on Hurricane Erma and the discussions on how powerful it is. The most cited metrics for hurricanes and typhoons appears to be wind speed and eye barometric pressure (see Figure 1). I decided to look around for hurricane and typhoon strength data and the Wikipedia turned out to have a page containing large number of tables for all the most intense typhoons and hurricanes in different regions of the world. I used Power Query to (1) import the tables, (2) clean them up, (3) combine them, and (4) rank the storms by air pressure. Continue reading
Posted in Excel, History Through Spreadsheets
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Baby Name Frequency Ranking Using Power Query
You may have noticed that many of my recent posts are focused on data processing and analysis. These recent posts reflect the fact that I am preparing for a career change as I near "retirement," and I plan on working in the data analysis arena. This means that I have been in serious Python, R, and statistics training. While I love working with Python and R, I keep finding myself drawn back to Excel and Power Query (aka Get and Transform) for quick, ad hoc analysis work. While this blog will look at the frequency over time of the name Mark, you can use the tool to generate the same chart for any name. Continue reading
Posted in History Through Spreadsheets, Personal
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Largest Counties in the US
I am currently building a retirement home in Itasca County, Minnesota. While at the construction site, I spoke with with a sheriff's deputy about law enforcement coverage for my area. He told me that there were only two deputies on duty at night covering an area larger than the state of Delaware. He also said that if I the deputies are tied up in the southern part of the county it can take a while for them to get to my place, which is in the the northern part of the county. I had never thought about the size of the counties in northern Minnesota, but there are some large pieces of real estate there. Continue reading
Thermal Calculation Example for a Simple Electronic Component
An circuit designer came to me yesterday with an interesting problem whose solution nicely illustrates how simple component thermal calculations are performed. He was seeking advice on calculating the junction temperature of a Schottky diode (Figure 1) used in a switched-mode power supply. Continue reading
Posted in Electronics
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US Navy Warship Mix
While driving home after watching the eclipse, I listened to the news talking about a collision between a US Navy destroyer, the USS John S. McCain (Figure 1), and a commercial tanker. A previous collision also involved a destroyer, the USS Fitzgerald. These stories have made me curious about how many of these ships the US Navy has. Continue reading
Posted in Excel, Military History
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Using Excel to Plot Year of Dedication and Locations of Confederate Monuments
I heard some discussion on television about all the Confederate monuments around the country and when they were erected. I decided to look for the data and plot it for myself. I very quickly found a document from the Southern Poverty Law Center that looked interesting and provided me some interesting data tidying and charting challenges. My focus here is on duplicating their chart of monuments dedications dates. This chart type is not a standard Excel type and I wanted to see how I could duplicate it. This workbook will be used in a charting seminar that I plan to present in a month or so. Continue reading
Change in US House Square Footage Over Time
My wife and I are about half-way through the construction of a 2100 square foot home in northern Minnesota. This weekend, my neighbors and I were talking about the area of houses being built today, and no one in the conversation had any data. I grabbed my computer, jumped on the Internet, and very quickly found data from the Census Department that answered my question. Like most census information, the data is in the form of screwy tables that need to be parsed to get into a form that can easily be plotted. This exercise gave me another excellent example to use when I train staff on the use of Excel's Get and Transform tool. Figure 1 was the result of my search. For those who are interested, my workbook is here. Continue reading
Posted in Construction
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Calculate Eclipse Path Width
Yesterday, a reader asked me how to compute the totality path width for the eclipse that will cross the US on 21 Aug 2017. I wrote a post on how to perform this calculation years ago. NASA has published a path width value of 114.7 km. This width will actually vary a bit as the shadow moves across the Earth because the distance change slightly between all the bodies involved. Also, the Earth and Moon are not perfectly round, which I assume. NASA has very detailed models that even include the variations due to mountains and valleys on the Moon. Continue reading
Posted in Astronomy
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