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| SCIENCE & TECHNOLOGY |
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Trends Prof Yash
Pal THIS UNIVERSE |
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Solar
water heating Due to energy crisis in the country, it is imperative to use solar energy for water heating. The Ministry of Non-Conventional Energy Sources, Government of India is marketing flat plate solar water heating systems telling people that the useful life of the unit is 20 years, whereas the best manufacturers of the unit give guarantee for maximum five years of useful operation. Thus reality is somewhat different in practice. The P.G.I., Chandigarh unit, gave a useful performance of only one year and after that it became nonfunctional some time back, and remained so for a very long time. Flat plate solar collectors have a limitation. They have no concentration of solar insolation in them. They have poor performance because of heat losses. As such very low efficiency and in severe winter/cold conditions no performance at all they have when needed most. In reality we need hot water daily for needs in the family. It’s not a weather-proof arrangement. To overcome the difficulty, collectors can be designed on the principle of Cusp-Mirror-(Compound Parabolic Concentrator) where concentration of solar insolation is possible and the system’s performance can be much improved. However, heat losses are still there. Better would be a system where there is concentration of solar insolation and heat losses are almost eliminated altogether. The evacuated tube collector can provide the solution. It retains heat in much the same manner as a thermos bottle. Light energy strikes the collector, passes through the vacuum, hits the absorber tube, converts to heat energy and thus gets trapped inside. This retention of heat due to the vacuum allows the collector to reach high temperatures necessary in a variety of climates. Such collectors would be all-weather proof, even on cloudy or sub-zero days, thus collecting energy during daylight hours regardless of weather conditions. Such system would have to be based on the evacuated tube and the compound parabolic cusp reflector technologies. Below is given a diagram of such a system and is self explanatory. Such system would be quite costly — may be almost double the price of a flat plate collector because of the complicated and sophisticated technologies required in such systems. Even then it is worthwhile to go for such solar water heating, systems in the country. Flat plate collector is no solution. It only helps in sunny, warm regions for water heating. — The author is an Ex Professor of Mech. Engg.
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Microchips for monkeys Improving the life of captive animals in zoos may be easy as microchipping them and automating individual care routines. Scientists from The University of Queensland are developing an enrichment and husbandry system that can dispense food, toys and medicine depending on the needs of individually microchipped animals. Lead researcher UQ Gatton PhD student Julia Hoy said the system consisted of the microchips linked with scanners and other automated equipment that zoo keepers could set to release items at random times. Miss Hoy said this unpredictability would help enrich caged life. “The automated system involves microchipping animals so when they come to a scanner it will recognise each animal and then release food, sounds, smells, medications, toys or open a door controlling access to various parts of the enclosure,” Miss Hoy said. |
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Trends Using scores of telescopes, astronomers worldwide are chasing one of the most intriguing stellar explosions detected in nearly a decade. The supernova — a
catastrophic collapse of a massive star — is one of only a handful of these explosions known to have been heralded by a burst
of gamma rays. The observations confirm that material blasting out from a collapsing star generates a gamma-ray burst. The burst races out into space ahead of the visible, fiery glow from the supernova explosion. A gamma-ray burst typically lies too far away — billions of light-years — and has an afterglow too bright to permit astronomers to detect the underlying supernova. But the new burst, recorded by NASA’s Swift satellite on February 18, resided a relatively close 440 million light-years from Earth. Furthermore, the burst was unusually weak, despite lasting nearly 2,000 seconds — about 100 times as long as the typical burst. Cyborg sharks
DARPA (Defense Advanced Research Project Agency) has taken another page from science fiction writer William Gibson’s book by creating a neural implant to enable engineers to remotely manipulate a shark’s brain signals. This would eventually allow them to control the animal’s movements and possibly decode their perceptions. Given that sharks have senses that humans don’t have (like the ability to sense electromagnetic fields), it could open up some interesting uses. The implant consists of multi-channel neural ensemble readers and stimulators, diverse controllers and sensors. In addition, the DARPA researchers want to use their setup to detect and decipher the neural patterns that correspond to shark activities like sensing an ocean current, a particular scent in the water or an electrical field. If they can succeed in these experiments, it might be possible to control a free-swimming shark; it could be trained to track enemy ships or submarines, or to detect underwater mines or cables.
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THIS UNIVERSE Can stars exist in space without belonging to any particular galaxy? In other words, can they be isolated in space? Have such stars been discovered? I like your question. It is true that we do not see any stars alone in the large empty spaces between galaxies. A single star is tinier and more insignificant compared to a whole galaxy than is a single person when compared to the whole population of the earth. Such a star would be very lonely indeed as would be that single person. It is also hard to imagine how either of them could come into being in an empty void. Stars, like people, are also born. They have to be born out of something and it is difficult to imagine that that something would expend all its potential on a single star. If it is a star then, like people, it has to have its youth, maturity and old age. We do encounter such phases of life amongst the normal stars. Therefore, we cannot have lonely stars unless there is replenishment of such stars. One cannot think of the way this could be done, except by saying that they might be born within galaxies but for some reason they were banished from there and flung out to make their home in loneliness. It is hard to imagine processes that would do such a thing, even though there was a time when some astronomers advocated that the quasi-stellar sources with very large red shifts were actually stars that had been flung out of galaxies with high velocity! It does seem that in our universe it is hard to be alone. But I may be wrong and the universe might be full of entities widely distributed and away from the observable galaxies. For example, if there were entities that were once galaxies and were later eaten up by a black hole in the centre, we will certainly have something away from other galaxies. But this something would hardly look like an ordinary star. |
