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Monthly Archives: August 2017
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
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
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
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
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
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
I am preparing to drive out to Idaho to experience totality during the August 21, 2017 eclipse. I am choosing to view the eclipse from Idaho because my granddaughter (and her parents) live in western Montana, and I can stop there for visit when I return to Minnesota. This will be a long drive through large states (Minnesota, North Dakota, Montana) that have a significant percentage of farm land. While planning my journey, I became curious as to the percentage of farmland in each of the fifty states. In this post, I compute the farm land percentage by taking the farm acreage in each state and dividing by the state's land area (water area removed). Continue reading
I have been reading about how low natural gas prices have been affecting the coal mining industry. Coal mining is affected because those coal-fired electrical generation plants that can switch fuels are converting to natural gas to achieve significant cost reductions. Also, natural gas can fuel peaking generators that are designed to provide peak load support. I had no idea what the price advantages were for natural gas so I surfed over the US Department of Energy's (DoE) web site and found two tables that provided a summary of the maintenance, fuel, and operating costs for different types of electrical generation. Continue reading