Blog Archives

1st Qtr 2012

(c) 2012 Design/Analysis Consultants, Inc.
Newsletter content may be copied in whole or part if attribution
to DACI and any referenced source is prominently displayed with the copied material

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.

4th Qtr 2011

(c) 2011 Design/Analysis Consultants, Inc.
Newsletter content may be copied in whole or part if attribution
to DACI and any referenced source is prominently displayed with the copied material

This Issue: NEWS BITE: Rising Sun Gets Snagged On Mountain And Breaks Apart! / DESIGN MASTER TIP: Minimizing Calculation Time / ANALYSIS: Why Do A Worst Case Analysis? / TECH TIP: Nice Overview of Considerations for External Components for Switching Regulators / MORE UNINTENDED CONSEQUENCES: Wind Power Kills Endangered Species / ANALYSIS QUIZ: Adjustable 3-Terminal Regulator Output Tolerance

NEWS BITE: Rising Sun Gets Snagged On Mountain And Breaks Apart!
Motorists cautioned to avoid area due to high temperatures.

First planet with two suns reported found
15 Sep 2011, NASA and World Science

DESIGN MASTER™ TIP: Minimizing Calculation Time

Do an initial run and check sensitivities. Thereafter set the variables to their respective worst case values to reduce calc time until the design is finalized. Then set the variables back to their full range for a final calculation to obtain probabilities for risk assessment.

ANALYSIS: Why Do A Worst Case Analysis?

 
TECH TIP: Nice Overview of Considerations for External Components for Switching Regulators
See “Power System Performance Requires The Right Actives And Passives” by Tim Watkins, 8 Sep 2011 Electronic Design

MORE UNINTENDED CONSEQUENCES: Wind Power Kills Endangered Species

In the Bay Area, when activists in the 1980s demanded a cleaner planet, the state responded with the Altamont Pass Wind Resource Area. The state-approved wind farm, built with federal tax credits, kills 4,700 birds annually, including 1,300 raptors, among them 70 golden eagles…

“There’s a big, big hypocrisy here,” Sue Hammer of Tehachapi Wildlife Rehab in Kern County said. “If I shoot an eagle, it’s a $10,000 fine and/or a vacation of one to five years in a federal pen of my choice.”

From “Energy in America: Dead Birds Unintended Consequence of Wind Power Development” by William La Jeunesse, 16 Aug 2011, FoxNews.com

ANALYSIS QUIZ: Adjustable 3-Terminal Regulator Output Tolerance

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? (Answer will be posted in the next newsletter.)