IEEE Consultants' Network of Long Island

Ideas Needed - Dick LaRosa

On December 1, 2010 we had a presentation by Alan Adler, whose company, Cases by Source, Inc., makes carrying and shipping cases for high-value equipment. His other company, Source Packaging, Inc., makes those overly-large merchandize packages that discourage retail theft and tax our skills when we have to install a new print cartridge. It was obvious that he was the go-to guy on plastic foam and fabrication, so I asked him what it would cost to mass produce the approximately one-meter-square foam panel building blocks of the large solar-heated evaporator rafts that might be able to increase the humidity of coastal air flowing over mountains. This might be a help in the world-wide problem of insufficient precipitation on mountains that has been causing severe drought. My proposed design was a closed-cell foam a few inches thick for floatation, suitably reinforced by a metal or plastic frame with attachment ears to connect to adjacent panels of the raft. The top layer would be a dark-colored open-cell foam that would hold a thin layer of sea water to be solar heated and evaporated. Wicks would feed seawater up from the ocean beneath the foam.

Using Recursive Differential Equations - John Dunn, Consultant, Ambertec, P.E., P.C.

This circuit is a simple RC network being charged from a DC source for which a descriptive, first order differential equation is written and is then put into a software loop to simulate the actual process under consideration:

 

Sea Level in the Gulf of Mexico - Dick LaRosa

In my last post I reported that the difference in sea level between the entrance to the Gulf of Mexico (GoM) and the exit of the Florida Current (FC) at Settlement Point (SP) did not vary much with time, but the sea level difference driving the path segments upstream and downstream from Key West (KW) varied a lot more individually, and these two variations were complementary. What a complicated way to say that GoM sea level was rising and falling! Wilton Sturges of Florida State University pointed out that if the GoM level rises near KW, say due to a back up in the path from KW to SP, the rise in the GoM level will propagate as a wave counter-clockwise (CCW) around the Gulf near the shore but there might not be much change in level in the middle of the Gulf. The monthly average mean sea level (MSL) at KW has a peak-to-peak swing of as much as 43 cm over time intervals less than a year, and a long-term rise of 24 cm from 1913 to 2009. I would guess that this variation presents some problems to the wetlands and other features along the Gulf coast, including subsidence of the Mississippi delta.

Finding A Circuit Board's Short Circuit - John Dunn, Consultant, Ambertec, P.E., P.C.

You have some circuit board with a short circuit in it somewhere and just to make life difficult a'la Murphy's Law, that short circuit involves a foil that carries current to a whole slew of destinations.

A method for finding exactly where such a short circuit is located is illustrated by the following real life example.     

 

MILD-HYBRIDS AGAIN?--Carl Schwab

Mild hybrid is the term used to describe hybrid(?) schemes that in the main improve the trip mileage and performance in trip driving. The mild hybrid is a conventional car with a small electric mot/gen and a battery pack + controller and used in an "assist mode". We had a flurry of these some 10+ years ago and they faded away in favor of the PRIUS, Escape, Camry and GM-2mode type designs. This later group is marked by a LOCAL and TRIP driving mileage both good and about the same.

BER, brake energy recovery, in a mild hybrid is poor because the electric motor is too small and can't provide enough braking causing unnecessary use of the friction brakes----WASTE!

EXAMPLE OF GOOD BER: The GM IMPACT/EV1 used a 100 KW motor to provide acceleration, good, and hence also good braking, hence excellent BER.

NOTE: Torque generated as a motor is also available as torque for braking.

Headset Driver Oscillations - John Dunn, Consultant, Ambertec, P.E., P.C.

In an investigation into parasitic oscillation of some headset driver amplifiers, the equivalent circuit of a nominally eight-ohm headset was empirically examined using mimicry. The method is shown in the sketch below:    

 

A Neo-luddite Curmudgeon Reviews the New Kindle 3 - by Larry Rachman

Okay, I’ll admit it. I’m a late adopter when it comes to e-books. And I’ll admit to being prejudiced against them… or, maybe I should say in favor of traditional dead-tree technology. Yes, I’ve read a few books on my Palm cellphone, but it wasn’t a particularly rewarding experience. So, laying my cards on the table, I’ll say I’m coming into this predisposed to dislike the whole idea.

Having said that, I’ll have to admit that I’ve become rather enamored with the Kindle 3 after just a few short weeks of ownership. Sure, it has some shortcomings, but for the most part they’re shortcomings of e-books in general, not the Kindle in particular. But even after accounting for them, what’s left over is enough to make the thing a keeper.

First impressions:

The unit is small, light, and simple. It’s got a minimalist feel to it that’s uber-unintimidating. The e-paper screen is really quite impressive for anyone (eg. me) who hasn’t seen one before; it’s got a contrast ratio similar to paper, and a viewing angle pretty much equal to paper. And because it draws no power when not changing images, it’s never really ‘off’, in the sense that a CRT or LCD goes dark when there’s no image to display. When the Kindle is off, a decorative page appears. The display is so good that when I unpacked the unit for the first time, I mistook the image on the screen for a protective paper cover.

Avoiding Mental Burnout - John Dunn, Consultant, Ambertec, P.E., P.C.

How does one avoid mental burnout? What small, simple pleasures might one engage in when it now and then becomes necessary to lower the RPM on the mental tachometer? Lets just consider a couple.

Playing with words:

I once mentioned during a casual, family conversation, of having read of fossils of Homo Erectus that were found in a cave in China near that country's capital city. Because of their location and the time of their discovery, they were referred to as "Peking Man".

My father-in-law thought that was very odd because as far as he knew, peeking man had arisen as a result of the Judeo-Christian morality. I suggested probably not. I should have suggested that the rise was tied to technical advances in telescope design, but I was too slow to come up with that one when I needed it.

More playing with words:

Sea Level Puzzle - Dick LaRosa

The sketch below shows the continental shelf outline relevant to the Loop Current, Florida Straits, and Florida Current. NO denotes the location of New Orleans,   

RMS of A Square Pulse Train - John Dunn, Consultant, Ambertec, P.E., P.C.

You can find the root-mean-square (RMS) value of a unipolar square pulse train as sketched below using an average responding voltmeter, typically, a digital multimeter and a scope.

The RMS value equals the average value divided by the square root of the waveform's duty cycle:

 
While there are true-RMS meters that can conveniently yield this waveform's RMS value, such meters have crest factor limitations which become of concern for low values of duty-cycle. For this waveform, this method has no such limitation.