## Explaining A- and B-Basis Values

I’ve been thinking about how to explain an A- or B-Basis value to people without much statistical knowledge. These are the names used in aircraft certification for the lower tolerance bounds on material strength. The definition used for transport category aircraft is given in 14 CFR 25.613 (the …

## Blogging with Quarto

I’ve recently started using Quarto, which is a new open source project backed by RStudio. Quarto is a system for producing reports, presentations, books and blog posts. It takes text formatted with markdown and code written in Python or R and produces PDFs, HTML or several other formats that …

## Shear of Adhesive Bonded Joints

There are a lot of misconceptions about bonded joints. One of the misconceptions that I’ve seen most often is that people think that the average shear stress in a lap joint is predictive of the strength. This same misconception is usually phrased as either:

• Doubling the overlap length of …

## Violin Bow Stiffness

I’ve made a few violin bows and a couple cello bows. I’m very much a novice bow maker, but I’m learning. As I’m an engineer, I’m naturally trying to apply engineering principles to bow making, which isn’t necessarily easy since violin bows are actually …

Up until recently, I hadn’t really thought about the way that numerical integration was performed. Sure, I knew about some techniques like using the trapezoid rule to perform numerical integration, and without thinking about it too much, I had just assumed that the integration routines like R’s `integrate …`

## Long-Running Vignettes for R Packages

I’m going to release a new version of `cmstatr` soon. This new version includes, amongst other things, a new vignette. In R packages, a vignette is a type of long-form documentation. This particular vignette includes a simulation study that helps to demonstrate the validity of a particular statistical method …

## Calculating Extended Hanson—Koopmans Tolerance Limits

Calculating tolerance limits — such as A-Basis and B-Basis is an important part of developing and certifying composite structure for aircraft. When the data doesn’t fit a convenient parametric distribution like a Normal or Weibull distribution, one often resorts to non-parametric methods. Several non-parametric methods exist for determining tolerance limits …

## Basis Values From Censored Data

Earlier, I wrote a post about using a likelihood-based approach to calculating Basis values. In that post, I hinted that likelihood-based approaches can be useful when dealing with censored data.

First of all, what does censoring mean? It means that the value reported is either artificially high or artificially low …

## Basis Values Using a Likelihood Approach

All materials have some variability in their strength: some pieces of a given material are stronger than others. The design standards for civil aircraft mandate that one must account for this material variability. This is done by setting appropriate material allowables such that either \$90\%\$ or \$99\%\$ of the material …

## cmstatr: Composite Material Data Statistics in R

From what I’ve seen, a lot of the statistical analysis of data from composite material data is done in MS Excel. There are a number of very good tools for doing this analysis in MS Excel: ASAP, HYTEQ, STAT-17, and more recently, CMH17-STATS. I expect that the …

## Tracking Issues using Jupyter Notebooks

Edit (26-May-2022): This post is largely obsolete, now that GitHub is able to render math in Markdown documents, including issues. I’m keeping this post up for historical reasons, but I’d now recommend that you now use GitHub Issues directly and include mathematica notation as needed.

I’m currently …

## Pandoc Report Templates

The main benefit of using Notebooks (R Notebooks or Jupyter Notebooks) is that the document is reproducible: the reader knows exactly how the results of the analysis were obtained. I wrote about the use of Notebooks in an earlier post.

Most organizations have a certain report format: a certain cover …

## Package Adequacy for Engineering Calculations

If you do engineering calculations or analysis using a language like R or Python, chances are that you’re going to use some packages. Packages are collections of code that someone else has written that you can use in your code. For example, if you need to solve a system …

## Automating Software Validation Reports

I’ve been working on a Python package to analyze adhesively bonded joints recently. This package will be used to analyze adhesive joints in certain aircraft structure and will be used to substantiate the design of structural repairs, amongst other uses. Because of this, the output of this package needs …

## Reproducibility of Engineering Calculations

Reproducibility in engineering work doesn’t seem to get the attention that it deserves. I can’t count the number of times that I’ve read an old engineering report in search of a particular result, only to find that the calculation that lead to that result is only barely …

## rde: Now on CRAN

For the last couple of years, we’ve been using the statistical programming language R when we do statistical analysis or data visualizations at work. We typically deal with small data — most of the time, our data sets are high-tens or low-hundreds of rows of data.

A lot of the …

## Welcome to Kloppenborg.ca

Welcome to kloppenborg.ca

I plan to use this website as a blog where I discuss topics related to engineering, technology and whatever else I’m thinking about at the time.

If you find any of the posts here interesting, feel free to share them. If you don’t feel …