Wednesday, June 30, 2004

IEE Communications Engineer: Designing Buildings for the Wireless Age

Apparently this isn't online yet. Full citation: Alan Newbold, "Designing Buildings for the Wireless Age," IEE Communications Engineer v.2 no.3 (Jun/Jul 2004): 18-21.
I mentioned on my other blog about jamming or installing screening material to block mobile phone signals in libraries, theaters, etc. As emergency workers and "essential employees" go to their hiding spaces in buildings outside of the beltway, they have been planning on use mobile phones to maintain communications. Unfortunately, almost all buildings were not designed to take wireless communications into account. If I want to use my cell phone, do I have to go outside to get a signal? Some buildings have been retrofitted with repeaters.

On the other hand, internal wireless data networks can be snooped from across the street.

This articles discusses using frequency selective surfaces (fss) in building design to tackle these problems. Some of these surfaces are films for windows and reflecting material for walls that consists of a pattern of conductors on a dielectric substrate. If the walls have this dielectric substrate, low-pass filters can be installed to allow emergency communications frequencies through. Makes sense, but I wonder how many architects are taking RF into account? Also, what frequency band will we be using in 5 years? - News - Fiber gratings give abrasion alert

Andrew Gillooly has developed a wear sensor that uses a chirped fiber Bragg grating (CFBG). CFBGs have been used for temperature measurement and other sensor applications, but this is an inexpensive way to do wear sensing.The full article is from Measurement Science and Technology (TOC, PDF for subscribers)

Monday, June 21, 2004

Physical Review Focus: The Computer Minds the Commuter

"The model gives virtual drivers the option of cruising cautiously or speeding forward optimistically based on what they think the car ahead is about to do. Previous models haven't accounted for driver psychology in such a direct way. "
Another use of stat. mech. outside of physics: to model traffic. As you see above, this model improves on similar previous models because it doesn't have instantaneous acceleration and also models the "overreaction" of drivers. Does it model the complete jerks on the DC beltway, though? That's what I'd like to know.
Original article: Hyun Keun Lee, Robert Barlovic, Michael Schreckenberg, and Doochul Kim. "Mechanical Restriction Versus Human Overreaction Triggering Congested Traffic States" Phys. Rev. Lett. 92, 238702.

Tuesday, June 15, 2004

PhysicsWeb - Nanobulbs make their debut

"...physicists in China have now made a light bulb in which the conventional tungsten filament is replaced by carbon nanotubes. The new design has several advantages over traditional light bulbs and could be available in less than five years (J Wei et al. 2004 Appl. Phys. Lett. 84 4869)."
Finally a real, practical use for carbon nanotubes. These lightbulbs burn brighter with lower applied voltage and will probably last longer. - News - Sensor takes the drag out of flying (June 2004)

"Airspeed measurements are currently made using a number of finger-sized pitot tubes that protrude from the aircraft. They measure airspeed (the speed of the aircraft relative to the surrounding air) by sensing the impact pressure, the difference between static and total pressure. But this well established technology comes at a price. The probes cause drag and with aircraft operating lifetimes estimated at between 20 - 25 years, the associated fuel cost to the airline industry is huge"
It uses doppler shift (like lidar). Unlike other applications, they are trying to increase backscatter. To me, though, SOG (speed over ground) is a little more important and I assume they're using GPS for that. Ships use a pit sword which also creates drag. At the speed they're going, though, perhaps it isn't so important.
(I'm obviously using my new feeds from IOP, thanks guys) - News - Tiny projectors set for 2005 debut (June 2004)

"Pocket-sized projectors being developed by a Finnish company will make their commercial debut next year.
Upstream Engineering of Finland plans to release a pocket-sized color video projector onto the market next year. What's more, Upstream believes it can shrink the product down to the size of a matchbox within three years. These developments could pave the way for miniature projectors to be used in everything from mobile phones to laptop computers. "
Soon we'll have Power Point presentations going from our mobile phones/PDAs/cameras. This is definitely a better way to share information and will save the backs of many presenters.

Monday, June 07, 2004

IOP now has even more feeds

Use this page to find all of the IOP feeds on jobs, features, news, and magazine and journal tables of contents. Sort by category or look at recently updated feeds.

Thursday, June 03, 2004

(Wireless) Sensor Networks

There are sensors in just about everything: from biomedical devices to bridges. The in-style thing right now is Wireless Sensor Networks. After all, if we can all be wireless with tiny little devices, why can't the sensors. An easy way to see how mainstream this is is to scan the shelves of your local science library. The covers of two journals this month feature sensor network article(s):
Communications of the ACM, v47 n6 (June 2004). (link for subscribers)
Scientific American, v290 n6 (June 2004).(free preview, click here if you have Academic Search Premier).
These networks have been enabled by the miniaturization of the sensor and communications technologies, decreased power consumption, increased durability, and decreased cost.
Privacy activists worry that Big Brother will look more like the little computers in Crichton's Prey(Harper Collins, 2002). The "motes" are very simple, how do you guarantee they only tell you what they are sensing, not anyone with a receiver?
(updated to correct typos)

Science Daily: 17th Century Solar Oddity Believed Linked To Global Cooling Is Rare Among Nearby Stars

6/3/04 UC Berkeley-
"For 70 years, from 1645 until 1714, early astronomers reported almost no sunspot activity. The number of sunspots - cooler areas on the sun that appear dark against the brighter surroundings - dropped a thousandfold, according to some estimates. Though activity on the sun ebbs and flows today in an 11-year cycle, it has not been that quiet since. "
Sunspots are pretty important because of the potential impact they have on our climate, space missions, communications satellites, etc. There have been a few recent press releases about sunspots because of the Denver meeting of American Astronomical Society (AAS).
Another interesting one: "Groundbreaking Research To Improve Forecasts Of Sunspot Cycle" Science Daily, 6/1/04.
"Using a new computer model of the Sun, scientists have begun work on a groundbreaking forecast of the next cycle of sunspots. Mausumi Dikpati of the National Center for Atmospheric Research (NCAR) announced new research leading to an improved forecast of cycle 24"

Science -- NetWatch {28 May 2004; 304 (5675)}: Watching the Transit of Venus

This week Science points to several sites that will offer webcasts of the transit of Venus on 8 June. Venus will pass between Earth and the sun. You'll have to get up early, it starts at 1 a.m. Eastern!

Wednesday, June 02, 2004

Associated Press: Scientists Dig into Chesapeake Bay Impact Crater

6/1/04 (found via Topix)
"CAPE CHARLES, Va. (AP) _ Geologists drilling half a mile below Virginia's Eastern Shore say they have uncovered more signs of a space rock's impact 35 million years ago."
With all the talk of Bedout and Chicxulub, it's good that they're looking at our very own impact crater (the 6th largest in the world). The USGS press release is here. According to a recent workshop proceedings report (PDF, text), they are drilling to study:
  • Crater Structure and Morphology
  • Crater Materials
  • Impact - Postimpact Transition and Postimpact Events
  • Modern Deep Biosphere