1st Qtr 2012

(c) 2012 Design/Analysis Consultants, Inc.
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This Issue: NEWS BITE: Creepy Swarming Electronic Insects Are Real! / GOVERNMENT FOOLISHNESS and Incandescent Bulbs / WORST CASE ANALYSIS and the Fukushima Nuclear Plant Meltdown / RISK ASSESSMENT and Lithium Battery Explosions / ANALYSIS QUIZ: Answer To Last Quarter’s Question / DESIGN MASTER 8.2 UPGRADE if you’ve had troubling generating WCA reports on a Win7 PC

NEWS BITE: Creepy Swarming Electronic Insects Are Real!


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GOVERNMENT FOOLISHNESS: Incandescent Bulbs Banned? No Problem, Just Buy A Heat Ball
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From “Upset about Big Brother’s Ban on Incandescent Bulbs? Buy a Heatball!
by Selwyn Duke in the 30 Dec 2011 issue of American Thinker

For earlier Newsletter comments on the absurdity of banning incandescent bulbs, please see “Unintended Consequences: Nanny Engineering” in the 2nd Qtr 2011 issue.

WORST CASE ANALYSIS: What We Learned From Fukushima – Again

“Japan is not a technically backward country  … Its nuclear power plants were designed and built with an acute consciousness of extreme earthquake dangers.

“So how is it, despite that sophistication, awareness, and preparedness, that the Fukushima crisis has nonetheless exceeded worst-case thinking? Here, the story is reminiscent of Three Mile Island and Chernobyl, and the message seems to be the same: Worst-case scenario builders consistently underestimate the statistical probability of separate bad things happening simultaneously, as the result of the same underlying causes. [Emphasis added]
Japan Nuclear Accident Worse Than Worst, Again” by Bill Sweet, 12 Mar 2011, Energywise
Image: http://www.digitalglobe.com

RISK ASSESSMENT: Li-Ion Battery Pack Hazards and our Psychic Prediction

“Internal cell faults continue to lead to thermal runaway failures in Li-Ion battery packs used in the field. Though these events are rare, the proliferation of Li-ion-powered consumer electronics has increased the risk for an event occurring on an aircraft, or at a similarly inauspicious location or time … At present there is no [battery] pack-protection circuitry in commercial use that is designed to continuously monitor the cells for the symptoms of a latent incipient internal cell fault before such a fault causes thermal runaway.”
Detecting Lithium-Ion Cell Internal Faults In Real Time” by Celina Mikolajczak, John Harmon, Kevin White, Quinn Horn, and Ming Wu, in the Mar 1, 2010 issue of Power Electronics Technology

Even though there have been several fires and a few folks have been injured or killed due to exploding lithium batteries, we predict that the risk will be tolerated until a catastrophic explosion occurs. This will be  followed by the usual screaming headlines belatedly warning of the dangers, hind-sight experts suddenly popping up on TV, hand-wringing congressional investigations, and finally, heavy-handed and grossly over-reactive governmental regulatory responses.

ANALYSIS QUIZ (Answer from Last Issue): Adjustable 3-Terminal Regulator Output Tolerance

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An LM317T regulator with 36V input is set for 24V nominal output, using 1/8W 1% 100ppm thick film resistors (10K and 549 ohms). The regulator must deliver 1A and operate from 0 to 50 C for 10,000 hours.


Q: What will be the approximate worst case output tolerance?

-2/+2%        -4/+5%         -7/+6%         -6/+11%         -9/+15%

A: -9/+15%

Surprised? You might be if you only consider initial tolerances, and don’t factor in the effects of temperature and aging. Here are the normalized sensitivities, which gives one a better sense of the significant error contributors:

DESIGN MASTER™ 8.2 UPDATE: WCA Report Generator Bug Corrected

To facilitate the efficient creation of professional worst case analysis reports, Design Master includes an automated Word document report generator, based on Microsoft Office automation technology. We’ve recently had a few Win7 users notify us that the report function is not operable on their systems. Although Design Master has been tested on other Win7 systems with no problems, variations in Win7 system speed appear to prevent the report generator from functioning properly in some cases. Design Master Rev 8.2 allows more tolerance for speed variances, which has corrected the reported issues.

Posted on February 21, 2012, in Risk Assessment, Stress Analysis, Thermal and tagged , , , , , , , , , . Bookmark the permalink. 1 Comment.

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