Mechanical and civil engineers can lean on equations to make sure that the part will handle expected loads - but that is just step 1 of many. It's effectively the equivalent of "will it compile". After that step are many open questions around maintainability, reliability, costs, etc that have even more unknowns than the average software project. Engineering is an art based in science, no matter what the discipline.
Closing on the Toyota recall is very interesting, as it highlights the importance and complexity in engineering real time embedded systems.
- Cosmic radiation could cause a bit-flip resulting in a sudden acceleration event. Even though NASA and NHTSA could not find or demonstrate a problem with fly-by-wire, the issue was identified through expert analysis of the source code, which found that it did not follow best practices either. [0]
It also sheds light on the manufacturer's unpopular approach to these issues.
- The sticking accelerator issue discussed in the article only resulted in 3 complaints to Toyota in 2009 [1]
- Toyota sells 10 million cars a year. We can easily estimate that 50 million are on the road, placing this at or above Six Sigma reliability (3.4 dpmo)
Ultimately braking could safely override a stuck accelerator, still stopping in a safe distance in the most tests [1]
One could argue that the recall was more due to the PR backlash than any degrading part.
[0] http://www.sddt.com/Commentary/article.cfm?SourceCode=201311...
[1] http://en.wikipedia.org/wiki/2009%E2%80%9311_Toyota_vehicle_...
I had a friend that worked for an electronics test equipment manufacture, some of the systems they had were pretty awesome. If a component were off center by something like 1/1000 of a meter the visual inspection system would flag a board for review. The sped that it could find defects was amazing. No human could hope to keep up, so every part on the line could be inspected.
From design by contract, unit testing, integration testing, static analysis, formal proofs, dependent types...
Managers are not willing to invest the required money into development practices that use the techniques above.
Most consumers are not willing to pay for quality and will rather use the software version of 1€ shops quality, if it works most of the time.
Many cowboy coders see software development practices that lead to higher quality as ivory tower advocacy that only gets in the way.
Another important point is software engineering is a baby among the other disciplines. So in its first half century we've had a continuous stream of pitch men selling the new silver bullet that will fix everything, forgotten in a couple years of course. Oh but that NEW scam, its the real thing, this time, yup.
Compare to civil engineering, where the Romans were making great big piles of dirt 2000 years ago. Maybe not as well as we can or as fast as we can, but institutional experience does pile up.
Something to think about as a hard sci fi setting or similar, is a couple centuries in the future, being a programmer will be about as sexy as designing municipal sewer piping, and about as much room for creativity. So we should enjoy the fun while we can.
Quality is systemically controlling for variation. Repeat it, know it, love it. Even software benefits immensely from a systems view.
Deming would be all over this -- right up his alley. http://en.wikipedia.org/wiki/W._Edwards_Deming
Yes, that production bug may seem like the end of the world for you, but the vast majority of users probably won't even think of it.
Case in point: the time display on the train I commuted with today was off by an hour (DST I presume?) -- plus it had the date as "Oct 1st 2034". I'm not even sure anybody else noticed.
This resulted in vastly improved engine reliability.
Also, the analysis of failure modes in http://www.sportaviationonline.org/sportaviation/201001#pg94 is interesting. It turns out that most things do not work behave like the "If you chart failures over time, you will almost always see some form of bell-shaped curve" alluded to in the article. In particular, a discouragingly large fraction fail shortly after being put into service.
This is one reason why Boeing has made huge efforts to reduce the required maintenance on airplanes.
While computer analysis has replaced a lot of the "run, break, repeat" iteration, new engine designs will generally spend thousands of hours on the engine dyno before and concurrently with integration (road) testing before they're shipped in a model. While computer simulation has gotten pretty good, there's no substitute for the final product, especially when it comes to tuning engine control maps to pass emissions and develop power efficiently and safely.
The problem with ground coverings is that you generally expect it to be reliable and consistent if it looks like it should be. A single loose, chipped or cracked tile might be worse than an entire floor of them.
http://www.certainteedshinglesettlement.com/
I would imagine the failure modes are similar. They are marketed and guaranteed for 30 years, you actually get like 5 years, whoops.
These days many bikes carry ballast to bring them up to the limit.
The most significant change has been the shift towards aerodynamics. Component shapes have been optimised in ways that are far from ideal structurally, but provide considerable aerodynamic benefit.
A Cervelo S5 frame (optimised for aero) is 300g heavier than an R5 frame (optimised for weight). A set of 60mm-deep wheel rims might add 400g over a 30mm-deep pair, but pay for itself in drag reduction.
Weight reduction is still significant, but not purely for its own sake - saving weight allows you to 'spend' it on aero improvements. Notably, most time trial bikes are still well over the UCI minimum weight, because drag reduction is much more valuable than weight savings on relatively flat TT stages.
This isn't true. Bikes like OGE's Scott Addict or (last year's) Garmin-Sharp's R5/RCA are frequently ballasted. There'a video of Simon Gerran's Addict somewhere showing the ballast under the bottom bracket.
In the 2013 Female Giro Fabiana Luperini was disqualified after she finished 4th on a stage after her bike was found to be under-weight[1]
I agree with the rest of your comments to some extent. The weight limit has been great for other innovations, especially the use of power meters which would have never happened if it weren't for the weight limit.
But now-days but it's pretty easy to build an aero-framed bike under the weight limit, even for something like the S5 (which is hardly the lightest aero frame around). There's a guy who got under 6kg (12.96lbs = 5.87kg), admittedly using some fairly exotic parts[2]
[1] http://www.podiumcafe.com/2013/7/5/4496564/abbott-again-and-...
[2] http://weightweenies.starbike.com/forum/viewtopic.php?f=10&t...
If you drive in the US, and you're careful about it, the risks are probably around the same magnitude (in raw risks for all drivers and passengers, especially when done by distance, commercial flight is very much safer).
Only, as it turns out, it wasn't just Ford Explorers. GM vehicles on the same tires also had tread separations. Explorers running on Goodyear tires didn't have the problem.
For a good account of what went on inside Ford during the Wilderness AT crisis, read Jason Vines' What did Jesus drive?
