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Wednesday, August 22, 2007


All his life he has looked away... to the horizon, to the sky, to the future. Never his mind on where he was, on what he was doing. -- Yoda

JouleSort: A Balanced Energy-Efficiency Benchmark

The energy efficiency of computer systems is an important
concern in a variety of contexts. In data centers, reducing
energy use improves operating cost, scalability, reliability,
and other factors. For mobile devices, energy consumption
directly affects functionality and usability. We propose and
motivate JouleSort, an external sort benchmark, for evaluating
the energy efficiency of a wide range of computer systems
from clusters to handhelds. We list the criteria, challenges,
and pitfalls from our experience in creating a fair energyefficiency
benchmark. Using a commercial sort, we demonstrate
a JouleSort system that is over 3.5x as energy-efficient
as last year’s estimated winner. This system is quite different
from those currently used in data centers. It consists of
a commodity mobile CPU and 13 laptop drives, connected
by server-style I/O interfaces.

Read the paper here.

Google's paper on power provisioning for data centers

Large-scale Internet services require a computing infrastructure that
can be appropriately described as a warehouse-sized computing
system. The cost of building datacenter facilities capable of delivering
a given power capacity to such a computer can rival the recurring
energy consumption costs themselves. Therefore, there are
strong economic incentives to operate facilities as close as possible
to maximum capacity, so that the non-recurring facility costs can be
best amortized. That is difficult to achieve in practice because of
uncertainties in equipment power ratings and because power consumption
tends to vary significantly with the actual computing activity.
Effective power provisioning strategies are needed to determine
how much computing equipment can be safely and efficiently
hosted within a given power budget.

Read the paper here here.

Silicon nanoparticles enhance performance of solar cells

Placing a film of silicon nanoparticles onto a silicon solar cell can boost power, reduce heat and prolong the cell’s life, researchers now report.

“Integrating a high-quality film of silicon nanoparticles 1 nanometer in size directly onto silicon solar cells improves power performance by 60 percent in the ultraviolet range of the spectrum,” said Munir Nayfeh, a physicist at the University of Illinois and corresponding author of a paper accepted for publication in Applied Physics Letters.

A 10 percent improvement in the visible range of the spectrum can be achieved by using nanoparticles 2.85 nanometers in size, said Nayfeh, who also is a researcher at the university’s Beckman Institute.

In conventional solar cells, ultraviolet light is either filtered out or absorbed by the silicon and converted into potentially damaging heat, not electricity. In previous work, however, Nayfeh showed that ultraviolet light could efficiently couple to correctly sized nanoparticles and produce electricity. That work was reported in the August 2004 issue of the journal Photonics Technology Letters.

To make their improved solar cells, the researchers began by first converting bulk silicon into discrete, nano-sized particles using a patented process they developed. Depending on their size, the nanoparticles will fluoresce in distinct colors.

Nanoparticles of the desired size were then dispersed in isopropyl alcohol and dispensed onto the face of the solar cell. As the alcohol evaporated, a film of closely packed nanoparticles was left firmly fastened to the solar cell.

Solar cells coated with a film of 1 nanometer, blue luminescent particles showed a power enhancement of about 60 percent in the ultraviolet range of the spectrum, but less than 3 percent in the visible range, the researchers report.

Solar cells coated with 2.85 nanometer, red particles showed an enhancement of about 67 percent in the ultraviolet range, and about 10 percent in the visible.

The improved performance is a result of enhanced voltage rather than current, Nayfeh said. “Our results point to a significant role for charge transport across the film and rectification at the nanoparticle interface.”

The process of coating solar cells with silicon nanoparticles could be easily incorporated into the manufacturing process with little additional cost, Nayfeh said.

Saturday, August 18, 2007

Atanu Dey on ICT

Atanu is a development economist and a very perceptive individual. He also has a lot of common sense that's becoming increasingly rare in this information overloaded world. Atanu on the digital divide.

Friday, August 17, 2007

Supergyre identified by the Aussies

The aussies have broken new "ground" in identifying an undersea current that links the three southern hemisphere oceans. It would have been easier if they could ask a whale :)
From Science Daily
Australian scientists have identified the missing deep ocean pathway – or ‘supergyre’ – linking the three Southern Hemisphere ocean basins in research that will help them explain more accurately how the ocean governs global climate.The new research confirms the current sweeping out of the Tasman Sea past Tasmania and towards the South Atlantic is a previously undetected component of the world climate system’s engine-room – the thermohaline circulation or ‘global conveyor belt’.

Wealth from Oceans Flagship* scientist Ken Ridgway says the current, called the Tasman Outflow, occurs at an average depth of 800-1,000 metres and may play an important role in the response of the conveyor belt to climate change.

So, What's Life anyway ?

A startling discovery, something that makes you go back to first principles and question the very axioms on which your value system rests. Inorganic interstellar life ! Read on

From : Science Daily
Could extraterrestrial life be made of corkscrew-shaped particles of interstellar dust? Intriguing new evidence of life-like structures that form from inorganic substances in space have been revealed in the New Journal of Physics. The findings hint at the possibility that life beyond earth may not necessarily use carbon-based molecules as its building blocks. They also point to a possible new explanation for the origin of life on earth.Life on earth is organic. It is composed of organic molecules, which are simply the compounds of carbon, excluding carbonates and carbon dioxide. The idea that particles of inorganic dust may take on a life of their own is nothing short of alien, going beyond the silicon-based life forms favoured by some science fiction stories.

Now, an international team has discovered that under the right conditions, particles of inorganic dust can become organised into helical structures. These structures can then interact with each other in ways that are usually associated with organic compounds and life itself.

Thursday, August 16, 2007

Ultrafast quantum computer: optically controlled electrons

Some more on the rapidly expanding portfolio of controlled light. Qbits meet photons.

Susan Clark and Kai-Mei Fu, both of Stanford University, and Thaddeus Ladd and Yoshihisa Yamamoto, both with Stanford University as well as the National Institute of Informatics in Tokyo, have published their results on the new scheme in a recent issue of Physical Review Letters.

“We still don't know what a final quantum computer will look like,” Ladd explained to “Large scale quantum computation is a technology that is still very far away from being implemented, and will probably incorporate many new ideas that have not been imagined yet. The important development in this paper is finding a physical implementation of an existing theoretical idea [using phase gates to couple non-local spins] and estimating the speed.”

On a single semiconductor chip, the researchers combine fast single-bit rotations and fast two-qubit gates, both of which are optically controlled. In quantum computing, the orientation and phase of the electron spin serve as the bit state, and the gates are responsible for performing reversible operations on input data to produce output data.

The semiconductor chip is a square millimeter in size, and consists of a loop of cavities—together, this apparatus is called a “loop-qubus.” Each cavity holds a quantum dot, which is a small piece of semiconductor that contains, in this scheme, a single electron. By focusing optical pulses at individual quantum dots, the electron spins rotate, changing the state of the bit.

The architecture is built on the idea of using phase gates to couple non-local spins. The optical pulses can provide a means to couple distant electron spins, or qubits, so that the phase of one qubit can depend on the phase of another qubit. When coupled, the qubits’ spin states form a “qu-bus,” which is the basis of a two-qubit gate.

The operating speed of a quantum computer is measured by its clock signal, which could take many different forms. In the optical control scheme, the pulses, which could be supplied by a laser, provide a clock rate for the system. Ladd explained that there are several limitations on speed for quantum computers.

“In quantum computing, not only is the state of the bit (0 or 1) important, but also the phase of the bit,” he said. “How quickly we can control the phase of the qubit, in our scheme, depends on the magnetic field. Increasing the magnetic field increases how fast the phase for any single qubit changes in time and ultimately sets the limit of how fast we can control our qubits. In the article, we give the limit of about 100 GHz, which is assuming a very high magnetic field, which would require superconducting magnets to achieve.

“The second limitation on speed is the time it takes for the phase of one qubit to change the phase of another,” he continued. “This must be done with pulses that are slower than the rate light moves in and out of each optical cavity, so this brings the speed down to more like 10 GHz. Finally, as the computer gets bigger, the amount of time it takes for light to propagate around the system will also limit speed, perhaps bringing the speed of physical qubits down to GHz compared to classical computers.”

Friday, August 03, 2007

Lighting fixtures market to exceed $94 billion by 2010

LEDMag reports :
The worldwide market for lighting fixtures is expected to top $94 billion by 2010, according to a report by Global Industry Analysts, Inc.

The lighting industry encompasses industrial, commercial, residential and public lighting, and growth is expected mainly in the end-use sectors of construction and other industrial development activities.

The global lighting fixtures market comprises of several companies engaged in the development and manufacture of a range of fixtures from basic sconces to complex chandeliers. High quality and product innovation remain key competitive strategies for global majors, while price has emerged as a strong competitive platform in recent years.

The report says that solid-state lighting using LEDs and other technologies is expected to play a major role in lighting the future. Demand is to be stimulated by highly priced, technologically advanced and long lasting energy-saving products such as non-incandescent portable fixtures, high intensity discharge (HID) lighting, electronic ballasts, and portable fixtures using LEDs. The emergence of solid-state lighting technology that offers increased energy savings and advanced capabilities is poised to act as a significant challenge to existing lamps and fixtures manufacturers worldwide.

Europe currently represents the largest market in the global lighting fixtures market and is projected to cross US$23.5 billion by the year 2009. The Asia-Pacific region is poised to post the fastest compounded annual growth rate among the regional markets, at 6.5% over the ten-year analysis period.

The global lighting equipment market is expected to witness growth mainly in the end use sectors of construction and other industrial development activities. Another factor that is to contribute to growth of the market is booming end-use sectors in developing regions. Growth in industrialization and construction activities in these regions is spurring accelerated demand for lighting equipment.

Also, a rise in living standards, coupled with increased real estate activity, is expected to position China as the leading market for lighting equipment, with growth in the industrialized Western Europe and North America exhibiting less than global average. With the market in these regions mostly dependent on new construction activity, efforts are on to maximize energy efficiency in existing buildings.

Thursday, August 02, 2007

42.8 % and counting

A major landmark has been achieved by a team at University of Delaware. Static concentrator based Si solar cells have achieved 42.8 % combined efficiency. From renewable energy access :
In November 2005, the UD-led consortium received approximately $13 million in funding for the initial phases of the DARPA Very High Efficiency Solar Cell (VHESC) program to develop affordable portable solar cell battery chargers.

The highly efficient VHESC solar cell uses a novel lateral optical concentrating system that splits solar light into three different energy bins of high, medium and low, and directs them onto cells of various light sensitive materials to cover the solar spectrum. The system delivers variable concentrations to the different solar cell elements. The concentrator is stationary with a wide acceptance angle optical system that captures large amounts of light and eliminates the need for complicated tracking devices.

The VHESC would have immediate application in the high-technology military, which increasingly relies upon a variety of electronics for individual soldiers and the equipment that supports them. As well, it is hoped the solar cells will have a large number of commercial applications.

Today, the American soldier carries a pack that weighs nearly 100 pounds of which about 20 pounds are the three-day supply of batteries needed to power their gear. The DARPA program aims to dramatically reduce the battery logistics pipeline and provide the soldier with more power at reduced weight, thus improving mobility, survivability and the availability of advanced electronic technologies on the battlefield.