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Turning
walks into watts Prof Yash
Pal This Universe Remote
excavation of a gaseous planet Trends Largest animal eye New type of memory
circuit Quicker way to catch a
thief |
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Turning walks into watts Scientists in Canada and US have developed a generator, which can be mounted on the knee. It consists of an aluminium chassis and generator mounted on a customised orthopaedic knee brace, which produces electrical power from the swing of a walking person's knee. It looks like a simple knee brace and harnesses the power from part of the stride. According to its creator, J. Maxwell Donelan, professor of kinesiology at Simon Fraser University in British Columbia, the device works like the way that some hybrid-electric cars produce electricity from braking. The development of this biomechanical energy harvester is reported in February, 2008, edition of the journal Science. When we take a stride, there is a periodic motion of the leg e.g. acceleration and de-acceleration of the leg. The energy is required in both; for moving and braking. During walking, energy is dissipated at various places that go waste. We have to make up for this dissipation by performing work with our muscles. When we slow down the knee at the end of swinging of the leg, most of that energy normally is just wasted. It is this energy, which can be harnessed for generating electricity by the knee brace generator. The device does not capture the motion throughout the entire period of the stride because that would cause a dragging feeling with each step. To avoid this drag, the gear system of the device disengages at the beginning of the step and re-engages as the leg swings back from a stride. This means that the only drag occurs at the tail end of the stride, when muscles are actually working to slow the leg down. It does not detract from the energy required for moving forward, and in fact, by slowing down the leg at that stage of the stride, ends up relieving the muscles. below. According to Max Donelan and colleagues, the device is set in such a way that de-acceleration of leg could generate power without requiring much additional energy from the person. It is found that one minute of walk can produce electricity sufficient to power a cell-phone for 10 minutes. The 3.5-pound device on each leg can produce about 5 watts of electricity, enough to run cell phones and the medical devices such as insulin pumps or prosthetic limbs. With one generator on each knee, people walking on a treadmill were able to generate about 5 watts of power. The power generated could be stored in a battery. The first practical use for the generator is likely to be the power for artificial limbs. Although, the device won't reduce demand for oil, coal or gas power, but the energy while walking will not go waste and be potentially used to recharge iPods, cell phones, portable GPS devices, laptops computers, prosthetic limbs and other medical devices. The device could be used to power computers in remote regions where electricity is scarce. In another research reported in the journal Nature, the US scientists have developed a microfibre fabric capable of generating electricity. It produces enough current to recharge a cell phone, iPod and MP3 music player. If the fibre is made into a shirt, it could harness power from its wearer simply by walking around. This fabric consists of a nanogenerator, which takes the advantage of the semi conductive properties of tiny wires of zinc oxide. The wires are formed into pairs of brush like structures and shaped like a baby-bottle brush. One of the fibre in each pair is coated with gold so as to act an electrode. When a person strolls, the bristles brush together due to the body movement and convert the mechanical energy into electricity. These devices could prove to be a boon to hikers and soldiers, who have to carry heavy batteries (30 pounds) to run their high-tech gear for a 24-hour mission. These devices could be used either to replace batteries or extend their life, which might ease the burden on soldiers and increase their abilities in the field. The human body is a battery, which can be recharged with food. It is reported that there is about as much useful energy in a 35-gram granola bar as in a 3.5-kilogram lithium-ion battery. Finally, there is a saying-"Killing two birds with a stone", which proves true here. So, go for a stroll in morning and evening to power your gadgets and keep yourself fit.
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This Universe Why does an airconditioner
leak water? An airconditioner sucks in the outside air and passes it over fin-like projections, which have been cooled by the compressor. I assume that you know how the fins are cooled while the outside radiator is made very hot. (An airconditioner cools the inside while heating the outside). Now, back to your specific question. The outside air is not only hot but also often it is also quite humid. When passed over the cold fins, the temperature of air drops below the dew point and excess moisture condenses out. The external surface of a glass of cold ice water becomes wet for precisely the same reason or a bottle of cola taken from the refrigerator soon becomes slippery and wet. The glass or the bottle is impermeable to water. The water comes from the cooled air. The early morning dew on grass results because of the same process. At night, the earth cools more than the atmosphere. Moisture-laden air touching the cold ground cannot carry its load any more and deposits it on grass, in the form of glistening droplets. No, the air- conditioner does not leak in the conventional sense; it extracts the water from the air it is cooling. This process is particularly spectacular if your airconditioner is efficient and the humidity of the outside air is very high. I have always felt that we should find ways to harvest this distilled water, which is produced by the bucket-full, purely as a by-product. Does the ionosphere rotate with respect to the sun? If yes, does it rotate with respect to earth or it is fixed with respect to its magnetic dipole? Thank you for your letter and your query. All I can say is on the basis of some general arguments. It is obvious that if there were no sun there would be no ionosphere. Sun's impact is due to insolation, in visible, ultraviolet and even soft x-rays. All these produce ions. So there has to be a diurnal effect. Impact of the solar wind also makes a difference. This is apparent from the diurnal effect in cosmic rays, but in a more popular observation, that reception of long distance radio stations is clearer at night than during the day. This is partly due to the fact that at night time the ionosphere is relatively quiescent. There is also the observation that intensity of cosmic rays shows a 27 day cycle which is obviously related to the 27 day rotation period of the sun. Therefore the solar rotation and earth rotation are both implicated. I have a feeling that the ionosphere would give more respect to the magnetic dipole of the earth than its physical axis.
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Remote excavation of a gaseous planet It is not the search of aliens which is boosting the mission, but the discovery of another earth. Launched on October 15, 1997 from Cape Carnival, Florida, the Cassini-Huygens spacecraft is powered by thermoelectric power generators which generate electricity from the heat produced by natural decay of plutonium. It entered Saturn's orbit in June, 2004 through its F and G rings after traversing 2.2 billion miles. The NASA claims that the $ 3 billion mission has the most sophisticated spacecraft with 12 instruments on the orbiter and six more on Huygens probe, which was riding pillion to Cassini. If we analyse the data, its 'sent' box has 140,000 images and information gathered from 62 orbits of Saturn, 43 flybys of Titan and 12 of the other icy moons. So far, the most intriguing revelations, from the Huygens probe, are about the Titan, which has a dense atmosphere (1.5 times denser than the earth) full of liquid hydrocarbons, lake beds, channels, rain, rivers and snow. The fact that its atmosphere is rich in organic material and that living organisms as we know today are also composed of organic material would help in understanding how life on earth began. Then it has also been revealed about the interaction of Saturn's rings with its satellites. Straw like clumps on the A Ring, atmosphere of oxygen on rings and slowly rotating ring particles have also been discovered. The Enceladus moon, which is the highest priority target of the extended mission, has geysers, jetting out water-ice and feeding the most expansive ring of the Saturn. On being asked why Saturn is important, Carolina Martinez, spokesperson of the Jet Propulsion Laboratory, California, replied to this reporter that the Saturn and its ring system serve as a physical model for the disc of gas and dust that surround the early Sun and from which planets formed. She added that the success of searches for other planetary systems elsewhere in our galaxy partly depends upon how well we understand the early stages of the formation of planets. So by understanding how Saturn formed its various rings, we might learn more about our place in the solar system. Throwing more light on the implications of the Mission, Sandeep Sahijpal, an astrophysicist and senior lecturer, Physics department, Panjab University, said, "There is a frost-line which separates rocky planets, which are small, and big gaseous planets like Jupiter, Saturn. The 'ringed' planet, which is lighter than water, has around 60 satellites that revolve around it, presenting a kind of a solar system of its own. And there are gravitational-tidal interactions, which make it a special case."
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Trends The dream of producing spider silk in industrial quantities has come a step closer to reality after scientists managed to mimic the way silk protein is spun naturally into fibres that are potentially stronger than steel. Researchers have been trying to make artificial spider silk for decades because of its unusual and potentially lucrative properties. In addition to its extreme tensile strength, spider silk is highly elastic, and has the added advantage of being biodegradable. In the past, engineers have suggested a variety of potential uses of the silk, from bullet-proof vests and lightweight material for parachutes, to extremely strong ropes and fishing nets that will decompose quickly if lost at sea. But the main sphere of interest is in medicine, where extra-fine threads made of spider silk could be used as biodegradable sutures for sealing up internal wounds, according to Professor Andreas Bausch, who led the latest study at the Technical University of Munich.
The Independent
Largest animal eye
One of the squid's two eyes, with a lens as big as an orange, was found intact as the scientists examined the creature while it was slowly defrosted at New Zealand's national museum, Te Papa Tongarewa. It has been preserved there since being caught in the Ross Sea off Antarctica's northern coast last year. "This is the only intact eye (of a colossal squid) that's ever been found. It's spectacular," said Auckland University of Technology squid specialist Kat Bolstad, one of a team of international scientists brought in to examine the creature. "It's the largest known eye in the animal kingdom," Bolstad told The Associated Press.
AP
New type of memory circuit
It took about 40 years to find it, but scientists at Hewlett-Packard said on Wednesday they discovered a fourth basic type of electrical circuit that could lead to a computer you never have to boot up. The finding proves what until now had only been theory -- but could save millions from the tedium of waiting for a computer to find its "place," the researchers said. Basic electronics theory teaches that there are three fundamental elements of a passive circuit resistors, capacitors and inductors.
Reuters
Quicker way to catch a thief
Federal researchers say they've developed a human identification test that's faster and possibly cheaper than DNA testing. It would be a handy new weapon in the arsenal for detectives, forensic experts and the military, though no one expects it to replace DNA analysis and its promoters say it is not intended to. The new method analyses antibodies. Each person has a unique antibody bar code that can be gleaned from blood, saliva or other bodily fluids. Antibodies are proteins used by the body to fend off viruses or perform routine physiological housekeeping. "DNA is a physical code that describes you ... and in many ways so are your antibodies," said Dr. Vicki Thompson, a chemical engineer at the Idaho National Laboratory who's been working with other researchers to perfect the test for the past 10 years. The scientists say an antibody profile can yield results faster and more cheaply and be performed in the field with minimal training.
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It has long been a dream of scientists in the field of biomechanics to harvest energy from the human movements. The energy stored in the body fat is immense and equivalent to a battery that weighs more than a ton. To tap this power, the earlier efforts have included shoe-mounted devices and systems that channel the energy from the bouncing motion of a backpack. These systems, however, have so far been able to produce less than a watt of energy and further their designs needed a very deep understanding of how people walk.
The National Aeronautics and Space Administration (NASA) has extended the sojourn of its camera on Saturn and its moons by two years. The Casssini-Huygens spacecraft will make 60 more orbits around the 'ringed' planet, including 26 flybys of Titan, seven of Enceladus, and one each of Dione, Rhea and Helene, which are the moons of the planet.
Marine scientists studying the carcass of a rare colossal squid said Wednesday they had measured its eye at about 11 inches across bigger than a dinner plate making it the largest animal eye on Earth.