cations.” The iron nearly eliminates
costly hysteresis effects that otherwise appear during the on-and-off
cycling of the applied magnetic field
that drives the refrigeration device.
In operation, when exposed to a
magnetic field, the gadolinium alloy
and other materials heat up as their
spinning electrons align with the field,
thereby magnetizing the materials
and raising their temperatures. When
the external field is removed, the
materials demagnetize (the electrons
revert to a disordered magnetic spin
state), and their temperature drops.
The two stage process forms the
magnetic refrigeration cycle.
Magnetic refrigeration is already
a potential contender for specialized
applications, such as cooling sensors
in spacecraft and the liquification of
gases. With additional development,
it could be extended to household
refrigerators and freezers, dehumidifiers, and air conditioners — which
now account for about 25% of
residential power use.
Intel EM64T processors.
Also introduced were the xw6200
and xw8200 models. All support
Windows® XP Professional and Red Hat
Enterprise Linux WS 3.0 operating systems. The xw4200, xw6200, and
xw8200 are priced at $849.00,
$1,399.00, and $1,799.00, respectively.
624 MHz Pocket PC
Dell has introduced three new
Axim handheld computers that
include Intel’s PXA270 processors,
Windows Mobile® 2003 Second Edition
software for Pocket PC, and Bluetooth®
wireless technology. Two of the three
configurations feature a combination
of Bluetooth and WiFi® 802.11b wireless. Bluetooth allows personal area
networking with computer systems and
Bluetooth-enabled devices such as
mobile phones, GPS receivers, keyboards, and other handheld computers. Integrated WiFi enables users to
Dell’s Axim handhelds employ Intel’s
PXA270 processor and are available
with wireless technology.
HP Introduces New
Continuing with now-typical evolutionary — rather than revolutionary — developments in the microcomputer industry, Hewlett-Packard
( www.hp.com) has introduced three
new machines. The HP Workstation
xw4200 is the entry level machine
aimed at engineers, artists, designers,
scientists, and other users who have
intense application demands, require
large, complex models or data sets,
and have multitasking requirements
or extensive graphic needs.
The xw4200 features Intel’s 925X
Express chipset and Pentium 4
processors with Hyper-Threading
technology and speeds up to 3. 6 GHz
with an 800 MHz front-side bus. The
new chipset drives the PCI-Express
graphics and input/output interface,
DDR-2 memory architecture, integrated Serial ATA RAID controller, and —
when available — support for future
Circle #76 on the Reader Service Card.