 |
|
| SCIENCE & TECHNOLOGY |
|
|
|
Electricity from noise pollution The real George
Washington
|
|
|
Electricity
from noise pollution We all know that it is possible to produce electricity from sound. Microphones are the simplest example. But we can use noise pollution for generating considerable amount of electricity. The idea is based on the same scheme as microphone but for the purpose of generating electricity we can think of a huge array of microphones installed near noisy places to perform like windmill. It is possible that sound waves at the kinds of noisy sites referred here would carry enough energy to generate economically useful amounts of electricity for everyday situations. Moreover, there are situations where small amounts of electricity generated from sound would be of value. Presently, even if we surrounded the noise place with devices capable of converting that noise into useful energy we would only capture a tiny amount of the total energy being available in the noise pollution zone and it would cost a lot of money to do it. However, it will be great to see this creative idea of converting wasted sound energy into useful energy working. Recent advances in energy conversion have also shown a great hope in this direction. Researchers from Los Alamos National Laboratory and Northrop Grumman Space Technology (USA) have built a compact generator that converts heat to electricity with the relatively high efficiency of 18 per cent. The generator uses a small version of a thermoacoustic sterling engine developed at Los Alamos in 1999. That engine converted heat to acoustic energy using no moving parts. Compressed helium cycles between heat exchangers, and the movement of the gas generated sound waves. In the generator, the sound waves from the engine drive a piston, which moves a coiled copper wire. As the wire moves through a magnetic field produced by a permanent magnet it produces electricity. Though noise is undesirable in general but it is indispensable in many cases of its generation. “Observe silence” slogans never fit to crowded places like bus stations, railway stations and airports etc. Noise pollution at such places can be put to a meaningful application if it can be converted into electric energy with the help of an array of microphones or thermo-acoustic engines. Microphones equipped with powerful magnets like “Neodymium magnets” can be made smaller, with more linear frequency response and higher output level. Let us hope that further scientific and technological developments in microphone technology as well as in thermo-acoustic sterling engine will improve the efficiency of sound energy conversion into electricity. The noise pollution which is a waste-resource thus can be put into the best use for mankind. |
|
The real George
Washington Americans know George Washington as the dour founding father with white hair and ponytail depicted on U.S. currency, but most people have little idea what the nation’s first President really looked like beyond this stock image. Researchers are hoping to change that by embarking on a massive detective hunt to flesh out his appearance in every detail. Specialists at Washington’s home in Mount Vernon, Virginia, 16 miles (25 km) outside Washington, are gathering dozens of artefacts including snippets of hair and clothing that will be analysed over the next year. Based on that information, they will make life -size models of the former President at three different points in his life that will go on display in 2006 as part of a new $85 million education centre and museum at Mount Vernon. Sculptures, moulds , busts dentures, imprints and masks of Washington’s face and body will be scanned with lasers. Hair samples,
spectacles, personal clothes and all available written descriptions of Washington’s physique, including those written by the President himself, will also be scrutinised. “We want to show visitors the real George Washington and showing visitors how he looked is critical to that goal,” said James Rees, Mount Vernon’s executive director. The scans will be merged and used to create detailed computer images that can be fine-tuned, said computer scientist and project participant Anshuman Razdan, director of Partnership for Research in Spatial Modeling (PRISM) at Arizona State University.
— Reuters
|
|
|
Understanding
the Universe
We know that the energy of the Sun is due to the fusion of hydrogen nuclei to form helium nuclei and this requires very high temperature. From where did the Sun get the energy to attain high enough a temperature for fusion to start? You are right in saying that the energy of Sun is produced through fusion. Fusion can occur only if the colliding nuclei have enough energy to overcome the electrical repulsion between like charges. This energy can be provided through thermal energy of nuclei at high temperature. Your curiosity is about the mechanism through which this high temperature is obtained in the first instance. The argument goes as follows: Stars are formed through condensation of large clouds of gas and dust. This condensation is due to mutual gravitational attraction. What you require is a small in non-homogeneous region that has more than the average density. This results in a greater attraction to that region. That which is slightly bigger keeps on getting bigger. Very much like the rich getting richer. There is a deep consequence. In falling together gravitational energy gets converted to kinetic energy of particles. These particles collide with other particles that are falling in. Motions get chaotic. That is heat, therefore the temperature rises. If the mass that accretes together is large enough, like that of our Sun or other stars, the release of energy can raise the internal temperature to millions of degrees. Higher the accreting mass greater the release of gravitational energy and higher the internal temperature. Higher the internal temperature greater is the rate at which the fusion of hydrogen takes place and hotter the star. There is a paradoxical consequence of this phenomenon. Larger stars consume their fuel at such a profligate manner that they might live only for a few million years, while our Sun will continue for at least another five billion years. The big one’s do not last long. They die earlier than the smaller ones. But let me step back a little to illuminate this discussion further. The question of stability of the stellar furnace has to be understood. How does our Sun continue shining with the same intensity? There is no computer control, nor any operator. The reason is simple and elegant. The start of fusion reactions in a collapsing cloud produces energy and increases the internal pressure. When this pressure equals the gravitational pressure of contraction the star becomes stable. Any decrease in the rate of energy production would decrease the internal temperature and hence the pressure. This would lead to a contraction of the star and hence an increase in temperature and pressure to restore stability. Similarly there would be an increase in temperature would increase internal pressure, leading to an expansion of the star and hence internal cooling. Sometimes it is said that Jupiter is a star that did not quite make it because it was not big enough. It still produces more energy than it receives from the Sun! This energy comes, perhaps, from continuous descent of helium under the force of gravity inside the core of Jupiter. Gravity is a very weak force as compared to the electrical and nuclear forces. However its influence dominates because it has the same sign for all forms of matter and energy.
|
|
| HOME PAGE |
Mummy secrets uncovered
Some Texas A&M University researchers examining ancient Egyptian mummies may have unwrapped - literally - some of the mysteries that embalmers used to preserve bodies more than 3,000 years ago. Mahlon “Chuck” Kennicutt II, MoonKoo Kim and Yaorong Qian of Texas A&M’s College of Geosciences, along with colleagues from the University of Alexandria, have discovered that tar originating from natural oil seeps in the West Asian area was used in the preservation and mummification process by Egyptians thousands of years ago. Their findings will appear in an upcoming issue of the Journal of Geoarchaeology. Examining areas near the Suez Canal, Kennicutt and the team also learned that tar fuelled fires in glass factories used by the surrounding communities.
Wind farms and climate
Large groups of power-generating windmills could have a small but detectable influence on a region’s climate, new analyses suggest. Windmills once were quaint several-storey-high mechanisms that pumped water or ground grain. They’ve since evolved into sky-scraping behemoths that can each generate electrical power for more than 100 homes. Some modern turbines are 72 metres tall and have rotor blades that are about 25 m long, says S. Baidya Roy of Duke University in Durham, N.C. Future windmills may reach higher than 100 m, and their rotor blades may measure 50 m long, he notes. All such turbines disrupt natural airflow to extract energy from wind. To investigate potential effects of a wind farm that includes thousands of windmills, Roy and his colleagues used a detailed climate model based on wind speeds, temperatures, and ground-level evaporation in north-central Oklahoma during a two-week period in July 1995. In their scenario, the researchers considered a 100-by-100 array of windmills spaced 1 km apart.
Melting glaciers
Mountain glaciers, which act as the world’s water towers, are shrinking at ever faster rates, threatening the livelihoods of millions of people and the future of countless species, a scientist says. Around 75 per cent of the world’s fresh water is stored in glacial ice, much of it in mountain areas, allowing for heavy winter rain and snowfalls to be released gradually into river networks throughout summer or dry months. “For some species and some people there are going to be big problems because mountain areas feed not just rural people but big cities, especially in Latin America,” said Martin Price of the UK-based Centre for Mountain Studies. In dry countries, mountain glaciers can account for as much as 95 per cent of water in river networks, while even in lowland areas of temperate countries such as Germany, around 40 per cent of water comes from mountain ice-fields, Price said. “It’s a huge issue in the long run because once the glaciers go, you’re down to whatever happens to fall out of the sky and come downstream,” Price told. |
The generator is simple, making it potentially long-lived and easy to maintain. This makes it especially appropriate for generating electricity aboard spacecraft, according to the researchers. The researchers’ next steps are to better match the engine and alternator to make the engine more efficient, and to reduce the engine’s volume.