All posts by Jeff Shelton

Episode 126 — Diesel Power

Aeronautical engineer Clay Coons joins us to discuss the many applications of diesel engines.

  • Adam’s Kubota BX tractor is powered by a 23 HP diesel engine.
  • During his high school years, Jeff learned that gasoline (petrol) engines don’t run too well on diesel fuel.
  • Ska Punk music often features horns, as evidenced on a song Carmen remembers from his youth, Sugar in Your Gas Tank by Less Than Jake.
  • Our guest for this episode is aeronautical engineer Clay Coons, who joined us previously on episodes titled Travel and Engines.
  • Diesel engines use compression, rather than a spark, to ignite air-fuel mixtures.
  • Modern diesel engines use turbocharging to compress the intake air being fed into the combustion chamber.
  • Diesel fuel contains about 14% more energy per unit volume than does gasoline.
  • Diesel engines operate at a rotational speed that is nearly half of that for a comparable gasoline engine.
  • Due to their relatively heavy weight, it is rare to find a diesel engine used for aircraft propulsion.
  • While nearly half the automobiles sold in Europe have diesel engines, that number is closer to 3% in the United States.
  • Anemic performance and poor reliability, associated with Oldsmobile diesel engines sold during the late 1970’s and early 1980’s, has been blamed for retarding North American diesel car sales over the past thirty years .
  • Adam asks about the use of diesel exhaust fluid (DEF).
  • In mining applications, a diesel engine can operate 25,000 to 30,000 hours between rebuilds.
  • Many heavy-duty trucks use the SAE J1939 standard for sharing information between vehicle components.
  • Our guest speaks highly of the cask ales he tried on a recent trip to Scotland.

Thanks to Ilya Plekhanov for use of the photo titled “BelAZ 75600 on Bachatskom Coal Mine, Kemerovo Region.” Opening music by John Trimble, and concluding theme by Paul Stevenson.

Episode 125 — Cubicle Farm

We discuss how the workplace environment influences our productivity in this episode of The Engineering Commons.

Thanks to Tim Patterson for use of the photo titled “I Love Cubicles…” Opening music by John Trimble, and concluding theme by Paul Stevenson.

Episode 124 — Mad Skillz

The gang discusses how one acquires the skills most frequently used by engineering professionals.

  • Brian knows that parliamentary procedures are described in Robert’s Rules of Order, but he has not had to use such procedures in the course of his engineering career.
  • A quorum is the minimum number of voting members from a deliberative group allowed to make decisions on behalf of that group.
  • This episode covers the skills commonly used by practicing engineers.
  • In 2001, Edward F. Crawley of MIT published a report that discussed engineering skills, titled “The CDIO Syllabus: A Statement of Goals for Undergraduate Engineering Eduation.” (pdf)
  • The top-level skill categories identified by Crawley were:
    1. Technical Knowledge and Reasoning
    2. Personal and Professional Skills
    3. Interpersonal Skills
    4. CDIO (conceiving, designing, implementing, and operating)
  • In 2003, Catherine Kelly studied the career paths of MIT undergraduates over a span of 35 years, producing a report titled “Some Trends in the Career Paths Followed by Alumni of the MIT Mechanical Engineering Department”. (link)
  • According to the Kelly report, approximately two-thirds of each graduating class from MIT’s Mechanical Engineering Department will find employment as engineers and managers. As the number of years beyond graduation increases, the percentage of engineers decreases, while the percentage of managers increases.
  • Georgetown University’s Center on Education and the Workforce published a 2011 study on STEM careers, noting that 10 years after graduation, 46 percent of STEM graduates have left the field.
  • Brian references a 2014 article from the ABA Journal claiming that 24% of those who passed the bar in 2000 were not practicing law a dozen years later.
  • Kristen Wolfe authored a 2004 thesis, “Understanding the careers of the alumni of the MIT Mechanical Engineering Department,” in which she surveyed MIT alumni about the skills they used in day-to-day engineering practice.
  • Brian notes that a good deal of his work involves trying to fight his own confirmation bias.
  • In 2015, Kelly Wang produced a thesis, titled “Study on the Careers of MIT Mechanical Engineering Undergraduate Alumni.” This report confirmed many of the findings from the 2004 Wolfe study.
  • In response to an email from listener Andrew, we’ve generated the following list of recommended YouTube channels:

Thanks to TechCrunch for use of the photo titled “TechCrunch Disrupt Europe Hackathon.” Opening music by John Trimble, and concluding theme by Paul Stevenson.