Author Archives: mathscinotes

Yet More Gift Wrapping

Posted on 16-December-2015 by mathscinotes

My sister and I talk about these practical math problems all the time. Here is another good video that covers gift wrapping with a mathematical slant. Continue reading →

Posted in General Mathematics | Comments Off on Yet More Gift Wrapping

A Couple of Cost Versus Run Rate Examples

Posted on 15-December-2015 by mathscinotes

I spend a fair amount of time estimating the cost of electronic components with different purchase quantities. In earlier posts, I showed how component cost quotes often reduce by ~7 % per doubling of quantity purchased. In this post, I will present quotes from two different vendors for the same part (normalized to preserve confidentiality). The component quotes from each vendor reduced by 3.6% per doubling of quantity purchased, which differs significantly from my 7% rule. While each vendor had different costs, their rates of variation with purchase quantity were identical. As I thought about these quotes, their deviation from what I usually see made sense. Continue reading →

Posted in Electronics, Financial | Comments Off on A Couple of Cost Versus Run Rate Examples

Not The Way To Take A Chimney Down

Posted on 13-December-2015 by mathscinotes

I have worked on construction sites and farms, and the lack of imagination that people show with respect to safety never ceases to amaze me. This video shows what happens when someone does not think about what could happen. Continue reading →

Posted in Construction, Humor | Comments Off on Not The Way To Take A Chimney Down

Network Availability

Posted on 12-December-2015 by mathscinotes

I was in an interminable meeting the other day where we were discussing the MTBF and availability of a system. My issue with this discussion is that each person in the room preferred to think about these terms in different ways. In this post, I will show that the four individuals in the meeting were actually in violent agreement and simply did not understand that what their arguments were mathematically equivalent. I wish I could say that this was the first time in my career that this had happened, but that would not be true. It happens all the time. Continue reading →

Posted in Electronics, General Science | 4 Comments

A Little Sandpaper Kirigami

Posted on 11-December-2015 by mathscinotes

I started using this sandpaper folding technique years ago, but I just ran across this video that does a nice job of illustrating the technique. Continue reading →

Posted in Construction | Comments Off on A Little Sandpaper Kirigami

Modeling Component Costs Over Time

Posted on 10-December-2015 by mathscinotes

I frequently am asked by marketing and finance people about how component costs will vary with time. Their motivations are clear – most market segments are strongly driven by unit cost, and the marketing folks need to determine when costs will drop enough to enlarge the Total Addressable Market (TAM) for their products. Continue reading →

Posted in Electronics, Financial, Management | 2 Comments

I am Battling Ladybugs This Year

Posted on 25-November-2015 by mathscinotes

We have had a warm winter in Minnesota so far this year. As with every transition from fall to winter, bugs seek warmth by taking up residence in our fiber-optic enclosures. Here is my latest example, a ladybug on a returned circuit board. Continue reading →

Posted in Electronics, Fiber Optics, Humor | 4 Comments

Modeling Coal Energy Output

Posted on 22-November-2015 by mathscinotes

I had never seen coal until my first trip to China when I saw people on bicycles transporting coal to their homes for heat. I started to wonder just how much coal a home would need for heating. I have seen numerous values for the heat content of the various types of coal. I recalled from primary school that there were three types of coal: anthracite, bituminous, and lignite. So I would have expected three values for the heat output of coal. When I actually looked, I found dozens of grades of three primary types of coal. Each of the different grades would generate different amounts of heat per kilogram. I thought I would take a closer look at how the heat output from coal could be modeled using regression and a simplified model based on chemical heats of formation. Continue reading →

Posted in General Science, Statistics | 1 Comment

Gross Margin Versus Labor and Material Markups

Posted on 21-November-2015 by mathscinotes

I have spent a fair portion of my career working as an engineering contractor. In fact, I spent five years working on new business development for a large contract firm. During this time, I was involved in writing dozens of proposals on large projects. A proposal occurs at the end of the bid and proposal process (Figure 1) and constitutes a contract firm's attempt to win the project development contract. It is a key part of new business development for many companies. Continue reading →

Posted in Financial | 1 Comment

Old Way Of Specifying Phone Wire Diameter

Posted on 20-November-2015 by mathscinotes

I still work on old copper phone networks, and today I encountered wire specified as "300 pound". I had never seen a specification like this for phone wire before. As I thought about it, this specification seemed very similar to how the diameter of thread is still specified, which is by the weight in grams of a 9000 meters of fiber – a unit of measure called the denier. Continue reading →

Posted in Electronics, General Mathematics, History of Science and Technology | Comments Off on Old Way Of Specifying Phone Wire Diameter