Chandigarh, Thursday, January 21, 1999
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Chandigarh, Thursday, January 21, 1999 |
| What made Titanic sink? by Nakul Chakoo and Pankaj Tandon The public has always been fascinated with the story of the oceanliner "Titanic" ever since she struck on iceberg during her maiden voyage on April 12, 1912, and sank with the resultant loss of more than 1,500 lives Spooky
teleportation study |
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What made Titanic sink? by Nakul Chakoo and Pankaj Tandon The public has always been fascinated with the story of the oceanliner "Titanic" ever since she struck on iceberg during her maiden voyage on April 12, 1912, and sank with the resultant loss of more than 1,500 lives. A surviving first class passenger of the ill-fated liner, Pierre Marechal, recalled: "When our boat had rowed about half a mile from the vessel, the Titanic — which was illuminated from stem to stern —was perfectly stationary, like some fantastic piece of stage scenery. Presently, the gigantic ship began to sink by the bows.... suddenly the lights went out, and an immense clamour filled the air. Little by little, the Titanic settled down and sank without noise. In the final spasm the stern of the leviathan stood in the air and then the vessel finally disappeared". For more than 85 years, the tragedy has been the subject off books, films and speculation as to why it took less than three hours for the ship to sink. Interest was renewed after Robert Ballard of the Woods Hole Oceanographic Institute found Titanic under 12,000 ft of water in 1985 and then again when the film Titanic opened in December, 1997. When the remains of the ship were discovered, it was found that parting of the plate seams made up the damage to the ship and that the up to 300 ft long gash thought to be created by the iceberg was only a myth. The ship was found broken into two pieces oriented in opposite directions. Some passengers had reported that the ship broke at the surface, as recollected by Elmer Z. Taylor who watched from Lifeboat No 5, close enough to the Titanic to observe its final demise. "The cracking sound, quite audible a quarter of a mile away, was due, in my opinion, to the tearing of the ship’s plates apart, or that part of the hull below the expansion joints, thus breaking the back at the point almost midway the length of the ship". But this was contrary to the reports of the disaster given by surviving officers, who testified that the ship sank intact. To help solve this mystery, in 1996 several samples of steel from Titanic — a hull plate from the bow area and a plate from a major transverse bulkhead — recovered from the wreck site, were subjected to metallurgical and mechanical analyses to outline several factors that could have played a role in the ship’s demise. Gibbs and Cox Inc, one of the oldest naval architecture and marine engineering firms in the world, conducted a basic study of the breakup of Titanic using linear finite element software (FEA) MSC/NASTRAN. This study was done in conjunction with materials testing of the Titanic steel by the University of Missouri — Rolla, with the advice from Prof H.P. Leighley Jr, Dr Timothy Foecke, and Mr Harold Reemsynder of Bethelehem Steel Corp’s Homer Research Laboratory in Bethelehem, Pa. In their study, engineers analysed the stresses in the Titanic as the flooding progressed within the bow regions, using modern finite element analyses (FEA) techniques that simply were not known to the structural designers of the ship in the first decades of the century. Under FEA study, a full-ship model was graphically constructed, employing modern graphic programming tools and then the corresponding weight and buoyancy curves were used to model the critical flooding conditions believed to represent the hull loading just prior to hull fracture. Since the flooding process took place over several hours, a quasi-static analysis (Analysis of a process that changes at infinitesimally small rate) was considered appropriate. The initial modelling effort focused on the determination of the location and magnitude of the high stress regions that developed in the hull while she remained on the surface. Engineers determined that stress levels in the mid-section of the ship were least up to yield strength of the steel just prior to sinking. When considered alone, stresses at these levels do not indisputably imply catastrophic failure. Additional analyses, focusing on probable locations of initial hull fracture, are required to indicate that the ship sustained possible catastrophic failure at the surface and began to break apart. Significant stresses were developed in the vicinity of the two expansion joints, and in the inner bottom of the ship between the forward end of the boiler room and the aft end of the reciprocating engine room. Structural discontinuities, such as expansion joints, result in stress concentration development. While these structural discontinuities have not yet been thoroughly investigated, it is believed that stresses developed at these locations were significantly higher than the material yield stress i.e. the Titanic’s hull girder stresses exceeded the yield point of the steel. Furthermore, metallurgical testing of samples of steel from the Titanic revealed a low residual nitrogen and manganese content and higher levels of sulphur, phosphorus, and oxygen than would be permitted today in mild steel plates. This indicates that steel was produced by open hearth rather than the Bessemer process, most likely in an acid-lined furnace; the steel is of type known as semi-killed, that is, partially deoxidised before casting into ingots. Excess oxygen can form precipitates that can embritte the steel, and will also raise transition temperatures. In the absence of sufficient manganese, sulphur reacts with the iron sulfide at the grain boundaries; it can also react with manganese, in either case creating paths of weakness for fractures. Sulphide particles under stress can nucleate micro cracks, which further loading will cause to coalesce into larger cracks; in fact, this was found to have been the mode of failure in the shell plating of the Titanic. Phosphorus, even in small amounts, has been found to foster the initiation of fractures. Of course, much of this metallurgical information has only been learned in the years since the the Titanic went down. To determine the steel’s mechanical properties, it was subjected to tensile testing, as well as the Charpy V-Notch test, used to simulate rapid loading phenomena; the test used samples oriented both parallel and perpendicular to the original direction of the hull plate. The ductile-brittle transition temperature was found to be 20°C in one direction and 30°C in the other, compared in — 15°C for reference sample of modern A36 steel and a water temperature of -2°C on the night the ship collided with the iceberg. The Titanic steel was shown to have approximately one third of the impact strength of the modern steel. When the Titanic samples were also examined with a scanning electron microscope, the grain structure of the steel was found to be very large; this coarse structure made it easier for cracks to propagate. Also, approximately three million hydraulically driven rivets were used to hold the hull sections of the Titanic together and it is believed that these rivets may be one of the main reasons why the ship sank. The wrought iron making up the rivets contained more than three times the amount of slag than would be allowed today. Apart from this, rivet holes were cold punched, a method no longer allowed (they must now be drilled), nor were they reamed to remove microcracks. It is suggested that upon impact with the iceberg, the rivet heads broke off, popped the fasteners from their holes and allowed water to rush in between the separated hull plates. The rivets examined from the samples of the Titanic were missing their interior heads. Photographs of the Titanic’s sister ship, the RMS Olympic, taken after it collided with another ship in 1911, support the theory. The photos clearly show vacant holes where rivets had once bee. The steel grain size, the oxygen, sulphur, and phosphorus content of the steel, the slag containing rivets, and cold punched, unreamed rivet holes were found to have contributed to breakup of the Titanic along with the steel’s relatively low ductility at the freezing point of water. The shell plates showed signs of brittle fracture, though some plates demonstrated significant plasticity. Of course, the science of metallurgy has advanced considerably since the Titanic’s day, the steel used in Titanic was the best available in 1909-1914 when the ship was built. In fact, when 39,000 tons of water entered the bow, no modern ship, not even a welded one, could have withstood the forces that the Titanic experienced during her breakup. The authors are
Post-graduate students from Metallurgical Engineering
Department, Punjab Engineering College, Chandigarh. |
Spooky teleportation study California researchers claim they have completed the first "full" teleportation experiment, reports Reuter. They say they have teleported a beam of light across a laboratory bench. They did not physically transport the beam itself, but transmitted its properties to another beam, creating a replica of the first beam. "We claim this is the first bona fide teleportation," Jeff Kimble, a physics professor at the California Institute of Technology, said. Kimble thinks the experiment shows quantum teleportation can eventually transform everyday life. Scientists hope that quantum computers, which move information about in this way rather than by using wires and silicon chips, will be infinitely faster and more powerful than present day computers. "I believe that quantum information is going to be really important for our society, not in five years or 10 years, but if we look into the 100-year time frame it’s hard to imagine that advanced societies do not use quantum information," Kimble said. Quantum teleportation allows information to be transmitted at the speed of light — the fastest speed possible — without being slowed down by wires or cables. The experiment depends on a property known as entanglement — what Albert Einstein once described as "spooky action at distance." It is a property of atomic particles that mystifies even physicists. Sometimes two particles that are a very long distance apart are nonetheless somehow twinned, with the properties of one affecting the other. "Entanglement means if you tickle one the other one laughs," Kimble said. In the weird world of quantum physics, where the normal ideas of what is solid or what is real do not apply, scientists can use these properties to their advantage. What Kimble’s team did was create two entangled light beams — steams of photons. Photons, the basic unit of light sometimes act like particles and sometimes like waves. They used these two entangled beams to carry information about the quantum states of a third beam. The first two beams were destroyed in the process, but the third successfully transmitted its properties over a distance of about a yard (metre), Kimble’s team reported in Science. Last December a team of physicists in Innsburck, Austria and a month later another team in Rome said they did a similar thing, with single photons. But Kimble said his team was able to verify what they had done, and also used full light beams as opposed to single photons. Although the Caltech team worked with light Kimble thinks teleportation could be applied to solid objects. For instance, the quantum state of a photon could be teleported and applied to particle, even to an atom. In other words, an object’s individual atoms would not be transported, but transmitting its properties could create a perfect replica. — PTI |
by J. P. Garg 1. In which city was the 86th Indian Science Congress, India’s largest and most prestigious gathering of scientists, held recently? To which type of sciences was the theme of the Congress related? 2. Name the 11-year-old wonder boy of Andhra Pradesh who, moved by the mass suicides of farmers in his state, presented a research paper on Integrated Pest Management at this Congress and has also developed a low-cost trap to attract and kill insects. 3. Now we have a robot that has senses and can show emotions like fear, anger, happiness and sadness. It has eyes, ears, mouth etc to show these expressions. What has this robot been named? Which main components does it use to interact with a human being? 4. Bar Code Scanner is a computerised device widely used in some countries in big departmental stores, libraries, modern manufacturing units, etc. By what other name is this device known? Who invented it? 5. Despite being harmful to human health and having been officially banned for use in agriculture as pesticides, DDT and BHC are still manufactured on a large scale and used extensively for spraying on vegetables and crops in India. What are the full chemical names of DDT and BHC? 6. This allotrope of carbon is used as a "moderator" in nuclear reactors and has a property that distinguishes it from other forms. Name this non-metal that has a metallic appearance. Which distinct property does it have? 7. Epsom salt is generally used as a medicine to treat constipation, heart burn etc. What is it chemically? 8. CAPES refers to an unusual kind of system of examination. What does CAPES stand for? 9. A forest in a test tube? Can you tell how many plant saplings can be grown in a normal test tube from a single plant using biotechnology? 10. Haryana will soon have a herbal garden where about five thousand plants of various species with medicinal values have been planted? Where is it being developed and which institute is developing it? Answers 1. Chennai; Biosciences
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Focused viewing US researcher has come up with a new system that exploits the limitations of human vision to focus that part of an image on a computer monitor or TV screen where the viewer’s attention is directed. Though computers can now show movies and upcoming digital televisions promise giant images that are crystal clear down to the minute details, most of the information used to make those big, complicated pictures is wasted, according to Joydeep Ghosh, electrical engineer at the University of Texas in Austin. Because of the limitations of the human eye, people cannot see a high-resolution image all at once (resolution is the maximum number of lines that can be discerned on the TV screen at a distance equal to the height of cathode ray tube). In fact, only a tiny piece in sharp focus is seen at any given moment, our brains than assemble these bits to give us the impression of a seamless, clear image. Ghosh wondered what the point is of making the whole television screen show a clear image, which requires the transmission and storage of a great deal of data, given that the eye will never be able to appreciate it. Ghosh and his colleagues have come out with a system that saves a lot of data space and bandwidth while displaying the image at a resolution that can be best perceived by the human eye, reports Discover. Superballoons as satellites Superballoons, which can float for months together in space and can reportedly take over some of the work of satellites for less than a tenth of present costs, are being developed by U.S. researchers. The new superballoons, being developed as part of NASA’s Ultra-Long Duration Balloon (ULDB) project, are designed to overcome a fundamental technological shortcoming of existing helium-filled balloons, reports New Scientist. Pressure inside and outside a balloon has to be kept equal to prevent stresses ripping the fragile envelope. However, the balloon loses helium during the day when the sun’s heat makes the gas expand and drops at night when the helium cools and contracts. "The only way to maintain altitude is to use ballast, limiting the time aloft to a maximum of three to five days at the latitude of the U.S.", says Steve Smith, ULDB project manager at NASA Goddard Space Flight Centre’s Wallops Flight Facility in Virginia. With the help of companies in the US and Japan, NASA has developed a lightweight material that is strong enough to withstand the pressure without venting helium. The fabric has three layers bonded together. The outer layer is woven polyester fabric, the middle layer is of mylar and the inner layer, of a polyethylene. The total thickness is about that of lightweight garbage bag. The superballoon, dubbed the "pumpkin" because of its odd flattened shape — it is 79 metres high, has a diameter of 128 metres and can carry a one-tonne payload at an altitude of 36 kilometres for up to 100 days. The total cost will be up to 3 million U.S. dollars. NASA will test a prototype in March and it hopes to launch its first working balloon by the end of 2000. Tough synthetic seashells US researchers have developed a synthetic seashell, a resilient material as tough as seashells, which could soon lead to scratch proof lenses or nearly unbreakable windshields. The achievement is another example of "biomimicry" — developing new products by drawing inspiration from natural processes or designs. The material is as strong as shells produced naturally by a family of mollusks using calcium carbonate and a natural polymer, reports Discover. The structural secret that makes seashells so strong is their alternating layers of rigid calcium and rubbery polymer. If a crack forms in one hard tier, it is quickly blocked by the neighbouring soft one, so that the damage cannot spread. It has been awkward and expensive to manufacture such a laminated structure, because it requires laying down a thin film of calcium then a film of polymer, then another film of calcium over and over. Jeffrey Brinker and Alan Sellinger at Sandia National Laboratories in Albuquerque hit upon a remarkably simple solution. They prepared a special brew of self-organising molecules and then dipped a silicon wafer into it for about ten seconds. After they removed the wafer, the excess solution evaporated leaving behind a transparent, seashell-like coating with interchanging sturdy and squishy layers. Hundreds of layers form at once depending on how fast the wafer is pulled out. Penny-sized CDs A small compact disc (CD) that can store data 800 times more efficiently than current CDs has been developed by an electrical engineer in the U.S.A. By drastically shrinking the already tiny data-coding pits on CD’s surface, ‘the new penny-sized CD, developed by Stephen Chou of Princeton University, can store five hours’ worth of movies, reports Discover. Current CDs are fabricated by injecting a liquid polymer against a mould that has data-coding bumps on its surface. These bumps — the mirror image of the pits that wind up in the polymer — are cut out with lithography, the process used to manufacture computer chips. But lithography uses beams of light, which cannot be used to etch patterns smaller than their wavelengths. Furthermore, the surface tension in a liquid polymer limits the ability of the substance to conform to bump below a certain size. To overcome these
obstacles, Chou turned to a process called electron beam
lithography to make the mould. Instead of light,
electrons were used to create the pattern. Electrons have
a much shorter wavelength than light, so they can make
smaller bumps. |
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