SCIENCE & TECHNOLOGY

Eco-friendly LED lighting
One of the main sources of global warming is the electricity generation as it requires burning of coal and other fossil fuels, which emit greenhouse gases. For the growth of industries, the consumption of power is increasing at an astronomical rate. The lighting is one of the sectors of power consumption, which eats 19 per cent of total electricity. In this sector, a lot of improvement is needed to enhance the efficiency of lighting devices, which will allow us to bridge the gap between the supply and demand of power.

Tapping energy from space
While great nations fretted over coal, oil and global warming, one of the smallest at the U.N. climate conference was looking toward the heavens for its energy.


Prof Yash Pal

Prof Yash Pal

THIS UNIVERSE
PROF YASH PAL
I am not a scientist. My grandson asked me why the full moon looks bigger at moonrise than when it is up in the sky. I explained it by saying that the thick layer of the atmosphere at the time of moonrise acts as a lens. The child was satisfied when I showed him that the lines on its hands looked thicker when seen through a lens. Was my explanation correct?

Trends
Stem cells from skin
A third team of researchers has found a way to convert an ordinary skin cell into valued embryonic-like stem cells, with the potential to grow batches of cells that can be directed to form any kind of tissue.

  • Teaching pandas to fight
  • Ship raised after 800 years

 


Top






Eco-friendly LED lighting
Dr Paul Singh

One of the main sources of global warming is the electricity generation as it requires burning of coal and other fossil fuels, which emit greenhouse gases. For the growth of industries, the consumption of power is increasing at an astronomical rate. The lighting is one of the sectors of power consumption, which eats 19 per cent of total electricity. In this sector, a lot of improvement is needed to enhance the efficiency of lighting devices, which will allow us to bridge the gap between the supply and demand of power.

Since the advent of electricity, the incandescent bulbs are the most widely used device for lighting purposes owing to their simple operation and low cost. But these are also the most inefficient devices as they convert only 10 per cent of energy into useful light and remaining 90 per cent of energy goes waste in the form of heat.

In the recent past, compact fluorescent lamps (CFLs) have been brought in use for lighting. These are more efficient than usual bulbs and convert 30 per cent of energy into light energy. A CFL can operate on only 20 per cent of the power of an ordinary bulb of similar output and has a life span 8-10 times that of a bulb. According to an estimate, switching to energy efficient lamps would result in 555 million fewer tonnes of CO2 emissions and 1560 million fewer barrels of oil consumed each year. This would be equivalent to putting off 530 power plants of 1000 MW each.

According to V.Raghuraman, Principal Advisor & Chief Co-ordinator, energy, environment and natural resources, the CFLs are not the panacea for lighting. After 10 years, more efficient light lamps like Light Emitting Diodes (LEDs) would come into picture and it would be possible to address the issue of hazardous mercury in CFLs.

LEDs deliver more brightness per watt and consume far less energy than traditional bulb. The LED lightings have life as long as 11 years, thus, virtually eliminates the need for replacement.

The latest LED light bulbs now produce about the same amount of light per watt as CFLs, which are supposed energy efficient. Unlike incandescent bulbs and CFLs, which throw light in all directions, LEDs are directional and drive the light in one direction, so that one gets the light exactly where it is needed. This directional lighting means savings in yet another way. The LEDs have already found use for following purposes:

  • In architectural lighting, Traffic lights and signals, Bike lights, Lights on emergency vehicles, Exit signs and Railroad crossing signals.
  • Status indicators on all sorts of equipment and movement sensors such as optical computer mice.
  • Remote controls for TVs, ACs and VCRs use infrared LEDs.
  • Continuity indicators like Elevator Push Button Lighting, Flashlights and Message displays at airports and railway stations.
  • Red or yellow LEDs are used as indicators in environments where night vision must be retained: aircraft cockpits, submarine and ship bridge.
  • Due their long life and fast switching action, these are used in automotive high-mounted brake lights, truck and bus brake lights. This increases the reaction time equal to one car length.
  • LED-based lights are in use on the eve of Christmas and Diwali. These lights are although costly but consume much less power to give the same amount of light as a similar incandescent bulb.
  • Computers use LEDs to tell the user its current state.
  • LED panel light source is used in an experiment on plant growth. The findings of such experiments may be used to grow food in space on long duration missions.

The first practical visible light emitting LED was developed at General Electric Company in 1962 by Dr. Shuji Nakamura of Nichia of Japan. He used a composite YAG phosphor coating on top of a blue LED, which converted blue light into white light. 

Top

Tapping energy from space

While great nations fretted over coal, oil and global warming, one of the smallest at the U.N. climate conference was looking toward the heavens for its energy.

The annual meeting’s corridors can be a sounding board for unlikely “solutions” to climate change - from filling the skies with soot to block the sun, to cultivating oceans of seaweed to absorb the atmosphere’s heat-trapping carbon dioxide.

Unlike other ideas, however, one this year had an influential backer, the Pentagon, which is investigating whether space-based solar power — beaming energy down from satellites — will provide “affordable, clean, safe, reliable, sustainable and expandable energy for mankind.”

Tommy Remengesau Jr. is interested, too. “We’d like to look at it,” said the president of the tiny western Pacific nation of Palau.

The Defence Department this October quietly issued a 75-page study conducted for its National Security Space Office concluding that space power — collection of energy by vast arrays of solar panels aboard mammoth satellites — offers a potential energy source for global U.S. military operations.

It could be done with today’s technology, experts say. But the prohibitive cost of lifting thousands of tons of equipment into space makes it uneconomical.

That’s where Palau, a scattering of islands and 20,000 islanders, comes in.

In September, American entrepreneur Kevin Reed proposed at the 58th International Astronautical Congress in Hyderabad, India, that Palau’s uninhabited Helen Island would be an ideal spot for a small demonstration project, a 260-foot-diameter “rectifying antenna,” or rectenna, to take in 1 megawatt of power transmitted earthward by a satellite orbiting 300 miles above Earth.

That’s enough electricity to power 1,000 homes, but on that empty island the project would “be intended to show its safety for everywhere else,” Reed said in a telephone interview from California.

Reed said he expects his U.S.-Swiss-German consortium to begin manufacturing the necessary ultralight solar panels within two years, and to attract financial support from manufacturers wanting to show how their technology — launch vehicles, satellites, transmission technology — could make such a system work. He estimates project costs at $800 million and completion as early as 2012.

At the U.N. climate conference here this month, a Reed partner discussed the idea with the Palauans, who Reed said could benefit from beamed-down energy if the project is expanded to populated areas.

“We are keen on alternative energy,” Palau’s Remengesau said. “And if this is something that can benefit Palau, I’m sure we’d like to look at it.”

Space power has been explored since the 1960s by NASA and the Japanese and European space agencies, based on the fundamental fact that solar energy is eight times more powerful in outer space than it is after passing through Earth’s atmosphere.

The energy captured by space-based photovoltaic arrays would be converted into microwaves for transmission to earth, where it would be transformed into direct-current electricity. — AP

Top

THIS UNIVERSE
PROF YASH PAL

I am not a scientist. My grandson asked me why the full moon looks bigger at moonrise than when it is up in the sky. I explained it by saying that the thick layer of the atmosphere at the time of moonrise acts as a lens. The child was satisfied when I showed him that the lines on its hands looked thicker when seen through a lens. Was my explanation correct?

I am sorry to tell you that your explanation was not correct. One can measure the size of the moon by using a simple survey instrument like a theodolite or, more simply by using a transparent scale at arm’s length — you might have to use torchlight to read the scale. You will find that there is no difference in the size of the full moon while it goes from moonrise to a high position in the sky! The difference we all observe is entirely psychological! The reason for this has been discussed extensively. Two of the explanations given are the following:

1) When we look at the moon near the horizon we also happen to see trees, people and buildings at the same time. Many of these are far away and look very small. But our brain knows that in actual fact they are much bigger. Therefore it automatically makes a correction in the observed size of the moon and makes us perceive it as bigger. I am not entirely happy with this explanation. Why only so much bigger?

Incidentally, the same observation is made in respect of the rising or setting sun and the very same explanation is given. Some day I would like to see the sun high up with a number of airplanes in the same field of view. I wonder if the sun would start looking bigger. If some of you have chance share this observations with me.

There is yet another explanation has been offered. We all have sensation that our sky is like dome. One could argue about the way this feeling came about but there is no question that we have that impression. In a dome the ceiling is never as far as its diameter. That is our experience of all the domes we have ever built. Therefore our brain places the moon or the sun near the horizon at a greater distance than when it is high up in the sky. It makes a correction for this difference and makes the moon or the sun look bigger near the horizon.

I have given you the explanations I am aware of. One thing one can definitely say - that there is no physical difference in size. It is all psychological. There is a long way to go before our brain really understands itself.

Does the intelligence of a person depend on the size of his skull? I am a student and do not feel comfortable in front of people who have bigger skulls than me.

I would straight away tell you to stop worrying. I know lot of very intelligent persons with small heads and a quite a few who have big skulls and are not so bright. All of us use only a small fraction of our processing power. I absolute terms it is not only the sheer size that matters but also the structure and folds. Even more brain needs nourishment and exercise, both physical and mental. Many of its powers develop through use and others die out if left unused. Just concentrate on that and stop feeling inferior when in front of swollen heads.

Top

Trends
Stem cells from skin

A third team of researchers has found a way to convert an ordinary skin cell into valued embryonic-like stem cells, with the potential to grow batches of cells that can be directed to form any kind of tissue.

Their study, published on Sunday in the journal Nature, shows the approach is not a rare fluke but in fact something that might make its way into everyday use.

Scientists hope they are starting an age of regenerative medicine, in which people can get tailor-made treatments for injuries, diseases such as Parkinson’s and diabetes, and in which scientists can study disease far better than before. — Reuters

Teaching pandas to fight

Scientists in China may use a police dog to teach pandas to fight after the first artificially bred panda released into the wild was apparently killed after a battle with other animals, local media reported on Saturday.

The Wolong giant panda breeding centre plans to have four pandas raised in captivity live with a specially trained police dog or other animals, the Chengdu Daily quoted reserve officials as saying. The officials could not be reached for comment.

The pandas would learn how to protect themselves by observing the dog, increasing their chances of survival when they were eventually released into the mountainous wilds of the far western province of Sichuan.

The world’s first artificially bred panda to be released, a 5-year-old male named Xiang Xiang, was found dead in the snow early this year after less than 12 months out of captivity.

Scientists believe he fell from a high place after getting into a fight with wild pandas or other animals over food or territory.

China is now preparing to release a second batch of up to four artificially bred pandas. Many or all would be females, which may be less prone to becoming involved in fights. — Reuters

Ship raised after 800 years

An 800-year-old merchant ship was raised from the bottom of the South China Sea on Saturday, loaded with artefacts that might confirm the existence of an ancient maritime trade route linking China and the West.

The 30-meter (100-foot) wooden vessel, containing thousands of gold, silver and porcelain trading goods, was hoisted onto a barge in a steel cage as high as a three-storey building, a live broadcast by national television showed.

Named the Nanhai No. 1 or “South China Sea No. 1” by archaeologists, the ship was discovered in 1987 off the coast of Guangdong province, buried in two meters (6.5 feet) of silt at a depth of 30 meters.

The Nanhai will be towed to a 150 million yuan ($20 million) museum built to house it in Guangdong, where it will be placed in a tank dubbed the “crystal palace” with the same water temperature and pressure that it experienced on the seabed. — Reuters


HOME PAGE

Top