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Author Archives: mathscinotes
Engineering Documents Should Not Be Like Snowflakes
I had dinner the other night with a networking engineer who works as a contractor. He is known as a person who writes well, and he is finding that many of the companies that he works for are asking him to determine how their networks operate and to write down what he discovers. Continue reading
Posted in Technical Writing
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A Quick Look at the Walmart Closings
I saw in the news that Walmart is in the process of closing 269 of its stores, including 154 in the US. I became curious where the US store closures were occurring, so I downloaded the closings file and generated a pivot table of the data (Figure 1). Continue reading
Posted in Management
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Book Review: Against The Tide
I have been working my way through a number of management books lately. The best of the lot, Against the Tide, was written by Admiral Dave Oliver about the management principles of Hyman G. Rickover (Figure 1). Years ago, I worked for a retired sub captain named Ernie Fischer. He had a number of interesting stories about serving on a nuclear submarine and about Hyman G. Rickover, the man responsible for creating the modern nuclear navy. Continue reading
Posted in Management, Military History
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Worked Calculation Example of Lithium Battery Capacity Versus Load
I frequently am asked to comment on data that other engineers send me. This morning I received some test data obtained from an engineer measuring the backup time of an Uninterruptible Power Source (UPS) containing multiple lithium-ion (Li-Ion) batteries. The engineer was disappointed with the backup time provided by this UPS and wanted to know if his test results were reasonable considering the battery capacity of the UPS. While there were numerous circuit parameters measured during this testing, the critical information was the battery voltage versus time. Continue reading
Posted in Batteries
21 Comments
Old West Cavalry Distributions of Age and Countries of Origin
When I was a boy, my father often told me stories of his grandfather, Louis Bauer, who was a member of the US Cavalry on the American Frontier. In fact, my father left my brother Tim the watch, spurs, and shaving cup that Louis used when he served in the cavalry. I used to wear the spurs for fun as a kid. Continue reading
Posted in History Through Spreadsheets, Military History
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Derivation of Pejsa Point-Blank Range Formula
A reader asked me if I could work through Pejsa's formulas related to calculating Point-Blank Range (PBR). During my earlier review of Pejsa's work, I chose not to cover this material just because it was not some of my favorite material – taste is definitely a part of mathematics. However, it is not difficult material to work through, and I like to answer questions when I can. Continue reading
Posted in Ballistics
2 Comments
Work Allocations Relative to the Ansoff Matrix
I am often asked to evaluate the focus of my team's efforts relative to company's priorities. There are different ways of expressing these priorities – one common approach is to look at how your group resources are allocated relative to the Ansoff matrix (Figure 1). Continue reading
Posted in Management
2 Comments
A Mathcad Utility Function for Air Pressure and Density
I have some work to do that requires a model for air density as a function of altitude, temperature, and pressure. As usual, I will turn to the Wikipedia to provide me a working model. I will then check the results of my model against results published by other sources. Continue reading
Posted in General Science
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A Most Unlucky Man
I watched an interesting video about the survivors of Hiroshima on CSPAN this weekend. While the main topic of the video was interesting, I was surprised to learn that there were a number of Americans POWs that were present at Hiroshima and died. They also mentioned an American POW that was near Nagasaki when it was bombed named Joe Kieyoomi. Joe, a Navajo soldier, has a war story that is almost unbelievable. Continue reading
Continue To Be Vigilant For Lead Exposure In Children
Last week, I had a conversation with a coworker about a mystery that he just recently solved that I feel is worth sharing here. He has a small daughter who recently was found to have high lead levels in her blood. As any good father would do, he tried to find the source of lead in his home. His home is new, so there is no lead paint in it. They tested everything that their daughter drank or ate, and they found no lead in anything – yet her blood's high lead level persisted. Continue reading
Posted in Personal
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