LISTEN To This Issue.
            Give your eyes a break; you can even listen at your own rate.

Quote of the Week.
            Visualizing the ultra tiny...

Getting From Here To There...
            It's called "Proximity Marketing," and it's very much technological.

Question of the Week - The Answer.
            One of life's little mysteries, revealed.
                 [Updated March 27, 2005]

Of Dubious Drinking Value?
            I'm not sure that 'I'll drink to that.'

About "The Harrow Technology Report"

LISTEN To This Issue.

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Quote of the Week.

 

"Transistors will soon be only 60 atomic layers thick.  'They are far smaller than viruses -- that's ALREADY nanotechnology.'

Kelly works with materials only five atomic layers thick, a width of 1.6 nanometers, where 1 nanometer is one billionth of a meter. It stretches human reason to comprehend dimensions that small."

So how can we visualize a nanometer?

"Take a 1mm-long object, say a house mite.

Imagine something 1,000 times smaller than the mite --

and then something 1,000 times smaller than that.

That's a nanometer."

University of Surrey Professor Michael Kelly,
in the April 25 SmallTimes
http://smalltimes.com/document_display.cfm?document_id=3547
(Brought to our attention by reader Dana Hoggatt)

 

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Getting From Here To There...

 

If you've been following the promises of new cell phone services that will be possible once our cell phones become "location-aware," then you've probably come across the decidedly mixed-blessing of "Proximity Marketing." 

This is the (useful or despicable, depending on your viewpoint) process of making your real-time position information available to marketers who might like to lure you into a restaurant you're approaching by offering you an instant discount, based on their current customer load.  Or to go even farther, using your credit/debit card shopping records to know that you're probably interested in [sports | electronics | clothing, take your pick] and offer you a special price on the 'latest and greatest' at the store that just happens to be at the foot of the next exit ramp (or the store farther down the mall).

The thing is, although I may sound disparaging of this idea, it could actually be useful to many people -- so long as we can strictly tailor (e.g., opt-in) and control its use.  For example, I might be very interested in being told about a 4-star Thai restaurant near me if it's near lunch or dinnertime, or I'd welcome a good price on a new DVD-recorder I might be contemplating.  But I would quickly become angry and discontinue the entire service if I was bombarded with come-ons from Indian restaurants (sorry, that's one of the few cuisines that don't sit well with me), or the latest prices on towels (unless they were high-tech, with built-in displays, etc...)  But you get the idea -- the service could be useful IF it's not abused (by MY definition.)

It's Already Here!

You may think these ideas are science fiction, but we see old sci fi themes showing up in the research labs and in the market seemingly every week.  And location-aware services are no exception.  But the first major use of location-aware consumer services in the U.S. has shown up in a seemingly unlikely place -- amusement parks.

According to the April 29 Newsweek (go to http://www.msnbc.com/news/741058.asp?cp1=1 and search within that page for "Step Aside"), a British inventor who was worn down by waiting for hours in the Orlando heat to get into a theme park ride, decided to do something about it.  He created a pager-like device that you can stick into a slot at a ride (or at many rides), and it will then beep and display information about which of your "ride reservations" is coming due. 

But this specialized device, using its infrastructure that was put into place throughout the amusement park, also provides location-awareness -- and these parks are getting some very good initial experience as to what works, and what doesn't, in Proximity Marketing. 

I can imagine them using your location to optimize your ride experience even farther, such as by noting that your time is coming up on a ride all the way across the park from you, while someone with a reservation at a ride near you happens to be closer to "your" ride -- it might then offer to swap your positions.  It's also obvious that with this technology, you'd rarely need to look for a cold drink as the temperature climbs, or for hot chocolate during Florida's one week of cold weather (I can throw stones -- I used to live there.)   And, kids can be fitted with active bracelets that will make it a snap to find them when they've wandered off within the park. 

These location-aware "walled gardens" would seem to be a prime learning environment for the cellular carriers, who intend to make this technology pervasive.
 

And It's Going Farther...

Of course, these amusement parks demonstrate just the beginning of the opportunities for location-aware services.  Consider Wherify's plans for a GPS-enabled tracking bracelet, and Applied Digital Solutions' plans for an implantable GPS device, both slated for the market this year! (http://www.wired.com/news/business/
0,1367,52253,00.html?tw=wn_ascii)   Even in today's "location-aware infancy," such services are already beginning to show up in cell phones.  They are, that is, you happen to be in Sweden, and if you and your friends sign up for the "FriendPosition" service.  Once you've done that, your phone will provide graphic and detailed textual information to let your group know where each member is. 

Why are the cellular carriers so interested in these add-on services?  Because, according to the May 2 Investor's Business Daily, the seemingly trivial $2/month charge for such services could represent $3.2 billion within the next four years!

For another example of how location-aware services are already becoming popular, consider this explanation of the cell phone-based "BotFighter" game, from Roberto Saracco of TiLabs:

"This is a game that uses localization systems and GSM phones. The game is a mixture of "action" and "role-playing", two areas that are of great interest to young people. The players locate each other and then "shoot" at people "in range" using their cell phone as their "gun;" the positioning system determines whether the distance is close enough to allow the "shot".

There is a special web site that houses a virtual community of robot enthusiasts where it is possible to purchase virtual weapons, to chat with other players, to see the scores, and to locate the different players in real time.  Then, if the player discovers that there is an enemy approaching his location, he/she can run down stairs and into range to start the battle.   But you don't need to be at a Web browser --  it's possible to get the position of an enemy by sending an SMS (text message) from your phone, and if the enemy is in the area, a further "shoot" text message will start the battle. The damage you do depends on the type of weapon used , the efficiency of the shield used by the enemy, and so forth. Each enemy destroyed wins you points in the score-list, as well as "coupons" that can be used to buy better munitions and weapons.

If the idea "intrigues" you, check out http://www.itsalive.com/ and click on "Games" and then "Where to Play" to find out if there is a virtual battlefield near you, although at the moment these are mainly concentrated in Scandinavia..."

Roberto also points us to another interesting use of location-awareness, in cars, as currently being explored in the Netherlands (all new cars there will be location-aware by 2006) -- it's called "variable-rate highway tolls," with the amount based on time of day, your location, traffic conditions, and other factors.  (See the interesting "MobiMiles" paper at http://62.250.16.6/beheer/HTMLbox/files/Mobimiles%20summary.pdf).  Already, companies and investors are paying careful attention to these emerging opportunities as evidenced by their attendance at a recent conference exploring the Netherlands' "RoadPricing" project (http://www.roadpricing.nl/item.asp?categoryID=5).  (If this really intrigues you, you can virtually attend the Netherlands conference at http://www.conferenceweb.nl/minvenw2002/venw.htm .)

Having to pay higher fees to drive to work is hardly a positive incentive for most of us.  But new services that will likely spring up in a fully location-aware environment may ease that pain.  For example, wouldn't it be nice to drive into town and be immediately directed to an open parking space?  Or how about being real-time-routed around accidents or other traffic problems, to provide the minimum-time drive to your destination?  And more. 

(We should remember, though, that all location-aware devices, which include the cell phones you use today to some extent, do open the privacy specter -- something that we're past-due in coming to grips with.  After all, we wouldn't want a Bot-Fighter to try shooting at his or her target with something more lethal than a cell phone...)

 

A Foregone Conclusion?

I think that it's clear that for both good and for ill, location-aware services are going to be with us.  I expect that over time, we'll wonder how we ever got along without them.  I just hope, though, that we all take care to assure that they're implemented in ways that we can, quite literally, live with.

Bottom line?  Technology is continuing its tenacious march into just about every aspect of our lives.  And while our societies tend to change far more slowly than Moore's Law, technology's hyper-exponential growth is forcing society to change at an increasing rate. 

The theme from the current "Star Trek Enterprise" series, "Faith of the Heart" by Russell Watson (http://www.enterprise13.freeserve.co.uk/star_trek_enterprise.wma), captures this progression rather well, particularly if you watch the show's introduction which adds poignant video to make the point:

"It's been a long road, getting from there to here. 

It's been a long time, but my time is finally near. 

I can feel a change in the wind right now, nothing's in my way.  And they're not going to hold me down no-more, they're not going to hold me down. 

Because I've got faith of the heart, going where my heart will take me.  I've got faith to believe -- I can do anything!"

Over time, our technology will indeed allow us to do almost anything, as we see here in The Harrow Technology Report, issue...after issue...after issue...

 

Back to Table of Contents

Question of the Week - The Answer.

 

Last issue, I tapped our collective knowledge to satisfy my curiosity (and from all indications, yours' as well) about the small, dumbbell-shaped things that we see on some power lines (http://www.theharrowgroup.com/articles/
20020429/20020429.htm#_Toc7673247 ).

As I expected, our community of Harrow Technology Report readers represents an incredible wealth of knowledge about almost anything technical, and clearly, many of you enjoy sharing your knowledge with others.  Answers started streaming in within minutes of publication, and although there's only enough room to share a fraction of the responses, these few samples will provide the surprising (to me) answer to this mystery.  Get ready to learn more than you might have wanted to know (but it's quite interesting) about these devices -- they're used to counter "Aeolian (wind-induced) vibrations," which are described in an easy-to-understand manner at http://www.uh.edu/engines/epi1653.htm (brought to our attention by reader Randy MacDonald).

(For a dramatic demonstration of Aeolian vibration, check out the automatic-playing (if slow to load) videos at http://georges.montefiore.ulg.ac.be/services/
tde/galop/Html/English/Types/main_typ.htm , brought to our attention by Chris Forsyt -- just mouse-over a video to start it.  They're worth waiting for.  Additional insights into this problem are at http://georges.montefiore.ulg.ac.be/services/tde/
galop/Html/English/Basics/main_bas.htm .)

 

Your Answers.

We'll begin with details from the first reader who put a name to these little beasties, "John":

They are called Stockbridge Dampers.

Their purpose is to stop the transmission lines from “dancing...”

These little odd things damp the vibration of the line and keep it safe and stable.

To find more, type “stockbridge dampers” into Google (http://www.google.com/search?hl=en&q=stockbridge
+dampers&btnG=Google+Search) and you will get about 539 articles on the subject.

Adding some detail, Abhijit Mukherjee, a Professor with Bombay, India's "Indian Institute of Technology," writes:

There is some virtue in being a Structural Engineer and reading The Harrow Technology Report! These "small barbell-shaped devices" are vibration dampers.

The transmission line conductors constantly experience wind induced vibrations, commonly called galloping. The vibration leads to fatigue of the conductor and possible breakage of the conductor. The dampers reduce the amplitude of vibration and increase the life of the conductors. They come in different shapes and sizes, although the barbell shape is most common. The necessity of installing these devices is dependent on the wind speeds of the location, the spacing of the transmission line towers and the type of the conductor.

 

How They Work.

But how can these seemingly simple devices actually work to dampen the vibration on the line?  New Zealand reader Roger Dunn, with a little help from that country's power consultancy "Power Line Solutions NZ Ltd." sheds some light on the "why" for us non-structural engineers:

"The spring steel wire supporting the dumbbell weights is constantly bent by the vibration, and so the energy is absorbed [by the movement of the weight]."

Eric Werme went further, pointing us to the Dulhunty Industries Ltd. Web site at http://www.dulhunty.com/html/home.html which includes more detail than most of us might care to assimilate, plus an interesting history of how the barbell design evolved (http://www.dulhunty.com/an1.htm).

 

Not Just On The Wires!

But perhaps even more intriguing is Eric's suggestion that the idea for these vibration dampers apparently originated from studying the fly (the annoying kind.)  It seems that some species have a similar balancing and vibration control appendage called the "haltere," as pictured on a page about genetic engineering at http://www.ultranet.com/~jkimball/BiologyPages/
H/HomeoboxGenes.html :

 

David Hutton and Paul Shearer both pointed out that these vibration dampers also show up in many places beyond power lines, such as on the long support spans for signs above major highways, as depicted in this picture courtesy of Peter Boleski, from a huge collection of road signs at http://www.aaroads.com/gallery/  :

Paul also adds that bridges use such devices to prevent oscillation of their suspension cables, such as this example used on a vertical bridge cable:

Least you think that taming Aeolian vibration isn't important, check out the description and pictures of the Tacoma Narrows Bridge disaster that occurred in 1940, at http://www.enm.bris.ac.uk/research/nonlinear/tacoma/tacoma.html .  For example, this picture caught the bridge undulating like a ribbon in the wind, just before it collapsed.   

A short video clip that will definitely drive home the power of wind-induced vibration is at http://www.enm.bris.ac.uk/research/nonlinear/tacoma/tacnarr.mpg .

 

An Expert Speaks Out.

Another reader turned to one of the experts who create software (PLS-CADD) used to design transmission lines in more than sixty countries - Otto J. Lynch, VP of Engineering Sales for Power Line Systems, Inc. (http://www.powline.com/).  He offers us the most comprehensive explanation of all, which gives us just a hint of the complexity of building the transmission system that, quite literally, lights up our world:

Jeff,

Your Question of the Week was forwarded to me by a friend of mine.  I am a transmission engineer and have designed many of those “transmission lines that crisscross our land.”  The items that you are curious about are simply vibration dampers.  As you know, transmission lines are strung at very high tensions – typically 3,000 to as much as 18,000 pounds under what we call “everyday” tensions, significantly increasing from there under other conditions such as wind and ice.  Tight wires will vibrate in the wind (we call it “Aeolian vibration”), and this vibration over time can cause fatigue and lead to failures in the conductor itself at the attachment points, or even sometimes in the hardware itself supporting the conductors. 

This vibration is extremely high frequency and usually cannot be seen by the naked eye – High Frequency / Low Amplitude.  These items, while they look simple, are simply placed at the first natural “node” away from the attachment point, and provide an inertial balancing to counteract the vibration.  You only need one of these per span, so on some lines, you’ll see one of these on both sides of every other structure.  On other lines, you’ll see one after each structure.  This really depends on the utilities' individual standards, the thought being that you reduce climbing / bucket truck labor if you just put them both on every other structure. 

The reason you don’t see these on all lines is that some lines are strung at lower tensions than others for various reasons.  The most common being very crooked lines with lots of angles and dead-ends; it is cheaper to reduce the tensions and have smaller (not as strong = less $$$) structures to handle those tensions.  A second reason for lower tensions is that you don’t have to put these things up!  With these lower tensions, the vibrations aren't as damaging and these dampers aren’t needed. 

However, line designs are most optimized when you can “chalk line” them long and straight, with little or no turning, and then crank up the tensions as much as possible.   The “magic” number for requiring these dampers is commonly accepted at above 18% RTS (Rated Strength) of the conductor at “everyday tensions”, with the code (NESC - National Electric Safety Code) allowing as much as 25% RTS under what we call “Final” everyday tensions.  On some lines with really high tensions or very long spans, you may see two, or even three of these dampers at the first or even several nodes out.

The industry slang term for these dampers is “dog bones”, as one of the early companies that made these made them look like dog bones and have theoretically proven that they provide better dampening that the ones you have in your picture. http://www.raychem.com/products/dulm_rrg/7-13.pdf  The plain shaped ones in your picture are technically called “Stockbridge Dampers”.

By the way, (while riding in your wife’s convertible) you may occasionally see a wire vibrating in a medium speed wind – usually smaller communications cables on distribution lines.  This is NOT Aeolian vibration – this is what we call “Galloping”, and is High Amplitude, Low Frequency, thus, you can see it.  There really isn’t much we can do about this type of vibration, and it is so rare (conditions have to be just perfect for it to happen) that it usually doesn’t cause too many fatigue problems, so we just space the cables apart far enough so that if/when this does occur, they won’t get too close together to hit, wrap, or even arc if they are energized cables.

...Many answers to your overhead line questions, and much more information about our software, can be found on our website at www.powline.com.  As you'll be able to tell, transmission and distribution line design is much more than just stapling wires to poles!

Finally, reader "dtalley" explains why "Power Lines for Dummies" books probably don't exist:

"I've never run across an introductory level transmission line book.  It's a mixture of civil and electrical engineering that's mostly taught on the job."

Ah, just like the old 'apprentice' days... 

There may not be a "Dummies" book available, but reader Jason George points us to the next best thing; an article at Marshall Brain's always-interesting "How Stuff Works" site (http://www.howstuffworks.com/power.htm). 

(If you'd like even more in-depth information on the electrical distribution grid, reader Roger Clark Williams points us to "The Lineman's and Cableman's Handbook" (http://www.amazon.com/exec/obidos/
ASIN/0070360111/qid=1020101180/sr=8-1/
ref=sr_8_1_1/103-8137482-0059061), while reader Rich Masiak suggests "Electrical Power Distribution and Transmission," at http://www.prenticehall.ca/books/ect_0132499479.html) .

 

And From Another Expert [March 27, 2005 update].

Our "knowledge community" never sleeps, it seems, as almost three years after this initial article was published another expert who works in the transmission line field has weighed-in with his analysis of some of the information discussed above.  So if you'd like to know more about the pitfalls of power lines and other things that are succeptable to wind vibration, here are Jean-Louis Lilien's comments, backed by his Website at http://www.montefiore.ulg.ac.be/services/tde/
new/recherche/recherche1/Basics/bas_fram.htm and http://www.montefiore.ulg.ac.be/services/tde/new/accueil.html .  You can continue this discussion with Jean-Louis at jl_lilien@hotmail.com .

"I’m working in Transmission and Distribution of Electrical Energy, I would like to point out the following points :

1)       You may have a look on (there is actually an error in the referencing of the website in some answers of the question on your web site)  www.montefiore.ulg.ac.be/services/tde which is actually under revision but you may read English explanation of the most frequent vibrations observed on overhead power lines in http://www.montefiore.ulg.ac.be/services/tde/new/
recherche/recherche1/Basics/bas_fram.htm

2)       The Stockbridge type damper visible on your question is only for Aeolian vibration type (low amplitude (a few mm), high frequency (5 to 60 Hz) vibrations), nothing to see with galloping type of vibration which may have up to ten meters amplitude (video on my web site).

3)       The Stockbridge type damper is designed to damp  with an available power close to a few Watts at the appropriate frequencies, its is tuned mainly on two major frequencies as the system is composed of two masses (this is a simple explanation, more available on demand). The position of the damper has to be studied to be close to the first anti-node (not node as stated in one answer) of the frequency on which the system is tuned. As frequency of Aeolian vibration is in the range of 5 to 60 Hz, the wave length is from a few tenths of meters to a few meters. For example a wave length of 10 meters at a frequency of 15 Hz would need to put a Stockbridge type damper at around 2.5 meters from the suspension point (this last being obviously a node of vibration).

4)       Aeolian vibration may cause very severe damage on conductor near a fixation point (like suspension clamp) as alternative bending in the conductor may induce fatigue and after a certain time some wires will be broken.

5)       Aeolian vibration need a wind speed less than  7 m/s roughly speaking, perpendicular to the cable and in flat terrain (over river, rice field, desert, fields, etc…). There are few vibrations in case of turbulent wind.

6)       Aeolian vibration origin, as explained on my web site, is linked to vortex shedding. The vortex shedding can tune its shedding with a frequency of vibration of the suspended cable (there are an infinite number of such frequencies, all following each other with 0.2 Hs proximity, roughly speaking), this is a fluid dynamics known phenomenon, the “lock in” and the frequency of vortes shedding is driven by the so called “Strouhal number” depending on conductor diameter and wind speed.

7)       It is important to notice that Aeolian type of vibration (for which Stockbridge type damper are used) has NOTHING to see with neither Tacoma bridge problem nor anything to see with galloping instability. Aeolian vibration is kind of forced vibration due to the vortex shedding which is giving, due to pressure changes on the conductor surface, alternating forced Perpendicular to the wind orientation. SO that for horizontal wind action, you have a vertical oscillation. You may damp Aeolian vibration with Stockbridge type dampers , there is NO hope to damp galloping with such dampers."

Thanks Jean-Louis.

 

The, Er, 'Alternate Approach?'

Oh -- of course there are some OTHER ways to look at these devices, such as this analysis from Paul Kinzelman:

"They're for recharging UFOs; these things make it easier for UFOs to attach to the power lines. :-)"

Hummm...

 

We Did GOOD!

Another one of life's little technological mysteries is now solved.  Many thanks to the huge number of you who responded, including to those of you whose responses would not fit but still added to this summary.  And I also thank you for demonstrating the value of a multidisciplinary approach -- I had assumed that the answer would come from the realm of electrical engineering, not structural engineering. 

We're all now a little bit smarter about the world around us...

 

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Your Feedback is Important!

 

I'd like to understand your interest in The Harrow Technology Report, how you make use of it, and the value you feel it provides to you, your career, and to your company.

Please send your comments to me at  Jeff@TheHarrowGroup.com  .

I look forward to hearing from you!

 

And, if you know of other folks who might find value in "The Harrow Technology Report," I'd appreciate your letting them know that they can subscribe at http://www.theharrowgroup.com/signup.asp .

Jeff Harrow

 

 

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Of Dubious Drinking Value?

 

Finally, it seems, according to the April 4 Excite News (http://news.excite.com/article/id/
152692|oddlyenough|04-04-2002::09:03|reuters.html , brought to our attention by reader Jeff Daly), that a Japanese firm has developed a transparent coating for a drinking glass that can measure the level of liquid in the glass. 

A prototype system from the Cambridge, MA labs of Mitsubishi Electric Research is going into a bar, where each pint stein will automatically report the level of the drink through a sensor buried in the table.  With this information, a waitperson can be "Johnny on the spot" to keep the beer drinkers (and the cash register) well supplied.

I don't know -- I can imagine many applications for a no-moving-parts way to measure the level of a liquid (the various fluid reservoirs in a car, numerous industrial uses, and more), but for a "never empty" beer stein?  Perhaps such a bar should be required to have patrons check their car keys before entering.

And imagine the hangovers...  

 

About "The Harrow Technology Report"

 

"The Harrow Technology Report" explores the innovations and trends of many contemporary and emerging technologies, and then draws some less than obvious connections between them, to help us each survive and prosper in the Knowledge Age. 

"The Harrow Technology Report" is brought to you by Jeffrey R. Harrow, Principal of The Harrow Group. http://www.TheHarrowGroup.com .

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Jeffrey R. Harrow maintains that all reasonable care and skill has been used in the compilation of this publication.  However, he shall not be under any liability for loss or damage (including consequential loss) whatsoever or howsoever arising as a result of the use of this publication by the reader, his/her/its servants, agents or any third party.

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