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Research
Summaries
UCLA Engineers Collaborate on Multimedia
Performance
By David Chute
Conceived and directed by Mel Shapiro, acting professor of theater
at UCLA’s School of Theater, Film and Television (TFT), “The Bloggers
Project” drew on a unique collaboration with the UCLA Henry Samueli
School of Engineering and Applied Science.
The text of “The Bloggers Project” was culled from real-life weblogs
combined with historical and literary material. Artists and engineers
from UCLA’s Center
for Research in Engineering, Media and Performance (REMAP) collaborated
to create the accompanying visuals.
Prompted by the show’s material and game-like concept, REMAP researchers
explored how the power of a modern game engine might be harnessed
to create a uniquely fluid world of media for a live event. During
its three brief months of pre-production, this effort brought together
a team of students and alumni from computer science, theater, animation,
cinematography, and architecture, led by REMAP executive director
Jeff Burke.
Original video segments were placed, together with found images,
in Epic Game’s Unreal engine to create a navigable three-dimensional
collage. This became the “world” from which each scene’s visuals
were taken during the rehearsal process. The raw material was composited
and layered onto an otherworldly architecture created by REMAP researchers.
Simultaneously, software was created to enable playback of the video
footage within the 3D world and allow the game engine’s perspective,
movement and media to be controlled remotely in real-time by an
operator watching the production.
To read more about the production, please visit http://bigriver.remap.ucla.
edu/remap/index.php/Blogger_Project.
New Silicon Optical Amplifiers Generate Electrical Power
by Harvesting Energy
By Melissa Abraham
Building on a series of recent breakthroughs in silicon photonics,
researchers at the UCLA Henry Samueli School of Engineering and
Applied Science have developed a novel approach to silicon devices
that combines light amplification with a photovoltaic — or solar
panel — effect.
In a study presented earlier this year, UCLA Engineering researchers
reported that not only can optical amplification in silicon be achieved
with zero power consumption, but that power can now be generated
in the process.
The team’s research shows that silicon Raman amplifiers possess
nonlinear photovoltaic properties, a phenomenon related to power
generation in solar cells.
“After dominating the electronics industry for decades, silicon
is now on the verge of becoming the material of choice for the photonics
industry, the traditional stronghold of today’s semiconductors,”
said Bahram Jalali, the electrical engineering professor who led
researcher Sasan Fathpour and graduate student Kevin Tsia in making
the recent discovery. It was Jalali’s lab that, in 2004, demonstrated
the first silicon laser, a device that took advantage of Raman amplification.
The amount of information that can be sent through an optical wire
is related directly to the intensity of the light. In order to perform
some of the key functions in optical networking — such as amplification,
wavelength conversion, and optical switching — silicon must be illuminated
with high-intensity light to take advantage of its nonlinear properties.
One example is the Raman effect, a phenomenon that occurs at high
optical intensities and is behind many recent breakthroughs in silicon
photonics, including the first optical amplifiers and lasers made
in silicon.
A fundamental challenge in silicon photonics is that the material
stops being transparent at high optical intensities, keeping light
from passing through.
“As light intensifies in silicon, it generates electrons through
a process called two photon absorption. Excess electrons absorb
the light and turn it into heat. Not only is the light and the data
carrying capacity lost, the phenomenon exacerbates one of the main
obstacles in the semiconductor industry, which is excessive heating
of chips. The optical loss also makes it all but impossible to create
optical amplifiers and lasers that operate continuously,” Jalali
said.
In previous attempts to deal with this challenge, a diode attached
to the chip has been used to “vacuum” out the electrons that block
light. This approach presents further problems, however, because
the vacuum adds an additional watt of heat onto the chip — nearly
a million times the power that a single transistor consumes in a
digital circuit.
“In the past, two-photon absorption in silicon has resulted in significant
loss for high power Raman amplifiers and lasers, reducing efficiency
and necessitating complex mitigation schemes. UCLA Engineering’s
new development will enable recycling power that would otherwise
be lost. In space and military laser systems, the impact of device
efficiency on electrical power and thermal management is a prime
consideration,” said Dr. Robert R. Rice, senior scientist at Northrop
Grumman Space Technology’s Laser and Sensor Product Center.
Silicon photonics technology has the potential to use the power
of optical networking inside computers and to create new generation
of miniaturized and low-cost photonic components, among other applications.
Read more about this research at http://www.engineer.ucla.edu/news/
2006/silicon amplifiers.html
Full-Scale Bridge Foundation Demolished for Earthquake
Safety Research
By Melissa Abraham
The collapse of a portion of the upper deck of the San Francisco–Oakland
Bay Bridge following the Loma Prieta earthquake in 1989 was a dramatic
illustration of the critical need for seismic safety on bridges
across California.
Now, a group of engineers from the UCLA Henry Samueli School of
Engineering and Applied Science are shaking things up in Los Angeles
in the name of earthquake safety.
In August, civil and environmental engineering professors Jonathan
Stewart and John Wallace and their team of researchers laterally
loaded a full-scale $1 million bridge foundation near Los Angeles
International Airport (LAX) to the point of failure in a quest to
improve engineers’ knowledge about how bridges react in earthquakes.
“These kinds of tests show us how bridges actually behave under
realistic conditions, so we can use what we learn to help develop
safer future designs,” Stewart said. “Lots of previous tests have
been conducted with reduced-scale models, but with those, you’re
still essentially guessing at how the real thing will react. Many
full-scale tests have also been conducted, but not to the point
of failure, which is what did here.”
The concrete bridge foundation, which stands five feet above ground
and reaches 25 feet into the ground below, is surrounded by 6-foot
hydraulic cylinders that have a stroke (or push-and- pull range)
of plus or minus three feet, and can move about 450,000 pounds each.The
cylinders, which exert roughly 2.4 million tons of force, can mimic
a small quake or can push the structure to endure “the big one.”
“We’ve built this full-scale bridge foundation and employed sophisticated
instruments so we can better understand what happens when we load
it to destruction,” Stewart said.“Our team has been working on loading
the foundation for some time, and so far we have only moved it about
a quarter of an inch. We expect that as we continue to load it with
more aggressive simulated earthquakes that it will give about four
inches, which is substantial when you’re talking about buildings
or bridges reacting to a temblor.”
Structural loads develop due to earthquake shaking and cause stresses,
deformations and displacements in structures, which are then analyzed
to improve future building designs. Overloading of the structure
during an earthquake is common, but the level of damage that results
depends on the structural design. Ultimately, Stewart and Wallace
hope their earthquake research will help all bridges to be designed
more safely and economically.
“Knowing exactly how we need to design bridges to withstand earthquakes
takes much of the guesswork out of it, which means we can fine tune
how engineers build,” Stewart said. “We can save lives, and secondly,
save money.”
The bridge foundation earthquake research has been ongoing for the
past five years and is being conducted in conjunction with CalTrans,
which funded the project. Students and researchers from UCLA Engineering’s
George E. Brown, Jr. Network for Earthquake Engineering Simulation,
or NEES, also have participated.
To read more about research in NEES, please visit http://nees.ucla.edu/.
Photos: Francois-Pierre Couture
Sasan Fathpour
Don Liebig, UCLA Photography
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