Monthly Archives: April 2019

Determining RMS Acceleration for a Vibration Acceleration Spectral Density

Posted on 27-April-2019 by mathscinotes

I was asked last week to write a vibration test plan for a mobile electronic product. I am used to writing vibration test plans that follow canned procedures in standards like MIL-STD-810F or SAE J1455, but this case is different because the customer has specified a non‑standard random vibration acceleration profile, which is also called a Power Spectral Density (PSD). I need to determine the RMS g level for this profile. This post shows how I go about this calculation. I am not going to showing the customer's vibration PSD because it is proprietary. Instead, I will use a well‑known US Navy vibration PSD as a computation example (Figure 1). Continue reading →

Posted in General Mathematics | 1 Comment

Let's Grow Some Oats

Posted on 21-April-2019 by mathscinotes

I am going to grow and process some oats this year. This is a project that I have been interested in doing for a while because one of my sons is now in the oat business and he has shown some interest in working through the entire oat processing cycle. As a boy, I used to mill oats on the family farm, but I remember very little of that time. Continue reading →

Posted in Excel, General Mathematics | Comments Off on Let's Grow Some Oats

Age of Supreme Court Justices at Confirmation with Power Query

Posted on 15-April-2019 by mathscinotes

I was listening to a political pundit mention that both US political parties want to confirm young Supreme Court justices to ensure that their judicial philosophies endure. I was curious as to whether that was true over time. I went to the Wikipedia and saw that they had a list of all the justices since the founding of the US and web pages for each justice. Sounds like a perfect opportunity for a bit of web scraping! Continue reading →

Posted in Civics Through Spreadsheets, Excel, History Through Spreadsheets | 2 Comments