kloppenborg.cahttps://www.kloppenborg.ca/Mon, 21 Nov 2022 00:00:00 -0500Explaining A- and B-Basis Valueshttps://www.kloppenborg.ca/2022/11/explaining-basis-values/<p>I&#8217;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 <a href="https://drs.faa.gov/browse/excelExternalWindow/B30DF8E84C71FFBD86256D7A00712EAD.0001">14 <span class="caps">CFR</span> 25.613</a> (the …</p>Stefan KloppenborgMon, 21 Nov 2022 00:00:00 -0500tag:www.kloppenborg.ca,2022-11-21:/2022/11/explaining-basis-values/postsComposite MaterialsRStatisticsBlogging with Quartohttps://www.kloppenborg.ca/2022/07/blogging-with-quarto/<p>I&#8217;ve recently started using <a href="https://quarto.org/">Quarto</a>, which is a new open source project backed by <a href="https://www.rstudio.com/">RStudio</a>. 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, <span class="caps">HTML</span> or several other formats that …</p>Stefan KloppenborgMon, 18 Jul 2022 00:00:00 -0400tag:www.kloppenborg.ca,2022-07-18:/2022/07/blogging-with-quarto/postsReproducibilityPythonRProgrammingShear of Adhesive Bonded Jointshttps://www.kloppenborg.ca/2022/06/bonded-joint-shear/<p>There are a lot of misconceptions about bonded joints. One of the misconceptions that I&#8217;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&nbsp;either:</p> <ul> <li>Doubling the overlap length of …</li></ul>Stefan KloppenborgSat, 25 Jun 2022 00:00:00 -0400tag:www.kloppenborg.ca,2022-06-25:/2022/06/bonded-joint-shear/PostsEngineeringPythonAdhesive BondingViolin Bow Stiffnesshttps://www.kloppenborg.ca/2022/06/bow-stiffness/<p>I&#8217;ve made a few violin bows and a couple cello bows. I&#8217;m very much a novice bow maker, but I&#8217;m learning. As I&#8217;m an engineer, I&#8217;m naturally trying to apply engineering principles to bow making, which isn&#8217;t necessarily easy since violin bows are actually …</p>Stefan KloppenborgWed, 15 Jun 2022 00:00:00 -0400tag:www.kloppenborg.ca,2022-06-15:/2022/06/bow-stiffness/PostsEngineeringBowSpeeding up Quadraturehttps://www.kloppenborg.ca/2021/09/speeding-up-quadrature/<p>Up until recently, I hadn&#8217;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&#8217;s <code>integrate …</code></p>Stefan KloppenborgSat, 18 Sep 2021 00:00:00 -0400tag:www.kloppenborg.ca,2021-09-18:/2021/09/speeding-up-quadrature/postsMathStatisticsLong-Running Vignettes for R Packageshttps://www.kloppenborg.ca/2021/06/long-running-vignettes/<p>I&#8217;m going to release a new version of <a href="https://www.cmstatr.net"><code>cmstatr</code></a> 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 …</p>Stefan KloppenborgMon, 21 Jun 2021 00:00:00 -0400tag:www.kloppenborg.ca,2021-06-21:/2021/06/long-running-vignettes/postsRProgrammingCalculating Extended Hanson—Koopmans Tolerance Limitshttps://www.kloppenborg.ca/2021/06/calculating-ext-hk-tolerance-limits/<p>Calculating tolerance limits &#8212; such as A-Basis and B-Basis is an important part of developing and certifying composite structure for aircraft. When the data doesn&#8217;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&nbsp;limits …</p>Stefan KloppenborgSat, 12 Jun 2021 00:00:00 -0400tag:www.kloppenborg.ca,2021-06-12:/2021/06/calculating-ext-hk-tolerance-limits/postsBasis Values From Censored Datahttps://www.kloppenborg.ca/2021/02/basis-values-censored-data/<p>Earlier, I wrote a post about using a <a href="https://www.kloppenborg.ca/2021/02/likelihood-basis-values/">likelihood-based approach to calculating Basis values</a>. In that post, I hinted that likelihood-based approaches can be useful when dealing with censored&nbsp;data.</p> <p>First of all, what does censoring mean? It means that the value reported is either artificially high or artificially low …</p>Stefan KloppenborgTue, 09 Feb 2021 00:00:00 -0500tag:www.kloppenborg.ca,2021-02-09:/2021/02/basis-values-censored-data/postsComposite MaterialsRStatisticsBasis Values Using a Likelihood Approachhttps://www.kloppenborg.ca/2021/02/likelihood-basis-values/<p>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 …</p>Stefan KloppenborgTue, 09 Feb 2021 00:00:00 -0500tag:www.kloppenborg.ca,2021-02-09:/2021/02/likelihood-basis-values/postsComposite MaterialsRStatisticscmstatr: Composite Material Data Statistics in Rhttps://www.kloppenborg.ca/2020/07/cmstatr/<p>From what I&#8217;ve seen, a lot of the statistical analysis of data from composite material data is done in <span class="caps">MS</span> Excel. There are a number of very good tools for doing this analysis in <span class="caps">MS</span> Excel: <a href="https://www.niar.wichita.edu/agate/Documents/default.htm"><span class="caps">ASAP</span></a>, <a href="http://www.niar.wichita.edu/coe/NCAMP_Documents/Programs/HYTEQ%20Feb%207%20%202011.xls"><span class="caps">HYTEQ</span></a>, <span class="caps">STAT</span>-17, and more recently, <a href="https://www.cmh17.org/RESOURCES/StatisticsSoftware.aspx"><span class="caps">CMH17</span>-<span class="caps">STATS</span></a>. I expect that the …</p>Stefan KloppenborgWed, 22 Jul 2020 00:00:00 -0400tag:www.kloppenborg.ca,2020-07-22:/2020/07/cmstatr/postsReproducibilityEngineeringComposite MaterialsRTracking Issues using Jupyter Notebookshttps://www.kloppenborg.ca/2020/04/tracking-issues/<p><em>Edit (26-May-2022): This post is largely obsolete, now that GitHub is able to <a href="https://github.blog/2022-05-19-math-support-in-markdown/">render math in Markdown documents</a>, including issues. I&#8217;m keeping this post up for historical reasons, but I&#8217;d now recommend that you now use GitHub Issues directly and include mathematica notation as&nbsp;needed.</em></p> <p>I&#8217;m currently …</p>Stefan KloppenborgSun, 12 Apr 2020 00:00:00 -0400tag:www.kloppenborg.ca,2020-04-12:/2020/04/tracking-issues/postsCollaborationPandoc Report Templateshttps://www.kloppenborg.ca/2019/10/pandoc-report-templates/<p>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 <a href="https://www.kloppenborg.ca/2019/06/reproducibility/">earlier&nbsp;post.</a></p> <p>Most organizations have a certain report format: a certain cover …</p>Stefan KloppenborgTue, 29 Oct 2019 00:00:00 -0400tag:www.kloppenborg.ca,2019-10-29:/2019/10/pandoc-report-templates/postsReproducibilityEngineeringRPythonPackage Adequacy for Engineering Calculationshttps://www.kloppenborg.ca/2019/06/adequacy/<p>If you do engineering calculations or analysis using a language like <a href="https://www.r-project.org/">R</a> or <a href="https://www.python.org/">Python</a>, chances are that you&#8217;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 …</p>Stefan KloppenborgSat, 29 Jun 2019 00:00:00 -0400tag:www.kloppenborg.ca,2019-06-29:/2019/06/adequacy/postsReproducibilityEngineeringRPythonAutomating Software Validation Reportshttps://www.kloppenborg.ca/2019/06/automating-software-validation-reports/<p>I&#8217;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 …</p>Stefan KloppenborgThu, 20 Jun 2019 00:00:00 -0400tag:www.kloppenborg.ca,2019-06-20:/2019/06/automating-software-validation-reports/postsReproducibilityEngineeringReproducibility of Engineering Calculationshttps://www.kloppenborg.ca/2019/06/reproducibility/<p>Reproducibility in engineering work doesn&#8217;t seem to get the attention that it deserves. I can&#8217;t count the number of times that I&#8217;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 …</p>Stefan KloppenborgThu, 20 Jun 2019 00:00:00 -0400tag:www.kloppenborg.ca,2019-06-20:/2019/06/reproducibility/postsReproducibilityEngineeringrde: Now on CRANhttps://www.kloppenborg.ca/2018/07/rde/<p>For the last couple of years, we&#8217;ve been using the statistical programming language <a href="https://www.r-project.org">R</a> when we do statistical analysis or data visualizations at work. We typically deal with <em>small data</em> &mdash; most of the time, our data sets are high-tens or low-hundreds of rows of&nbsp;data.</p> <p>A lot of the …</p>Stefan KloppenborgMon, 09 Jul 2018 00:00:00 -0400tag:www.kloppenborg.ca,2018-07-09:/2018/07/rde/postsRProgrammingReproducibilityWelcome to Kloppenborg.cahttps://www.kloppenborg.ca/2018/06/welcome/<p>Welcome to&nbsp;kloppenborg.ca</p> <p>I plan to use this website as a blog where I discuss topics related to engineering, technology and whatever else I&#8217;m thinking about at the&nbsp;time.</p> <p>If you find any of the posts here interesting, feel free to share them. If you don&#8217;t feel …</p>Stefan KloppenborgWed, 27 Jun 2018 22:00:00 -0400tag:www.kloppenborg.ca,2018-06-27:/2018/06/welcome/posts