Author Archives: mathscinotes

Countries That Are Graying Fastest

I have been working hard to address the issues associated with an aging workforce (blog post). However, aging is problem for the entire world – the median age of the world is increasing. Aging populations put enormous strains on the infrastructure of country. I have been reading quite a few articles lately on the effect of aging populations on quite a few developed nations: South Korea, China, Germany, and Italy. Many nations are facing the problems associated with aging populations: high medical expenses, providing elder care, paying pensions, etc. Continue reading

 
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Old Naval Mines Still Floating Around

I just read a news article about an old moored training mine washing up on a North Carolina beach (Figure 1). I am amazed at the number of mines that still wash up on beaches around the world. Figure 1 shows the mine that washed up on a North Carolina beach recently. Stories like this seem to happen frequently after severe storms. Fortunately, this training unit (i.e. inert) did not pose a hazard to the people who came upon it, but some explosive-laden mines still wash up on beaches (example). Continue reading

 
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WW2 Tank Production Comparison Between Combatants

Quote of the Day At least you figured it out. My first two husbands never did. — Female employee told me this after I mentioned that my wife's nickname for me was "The Paycheck" – this nickname was a joke … Continue reading

 
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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

 
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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

 
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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

 
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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

 
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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

 
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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 | 1 Comment

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

 
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