1. Advantages of helical gear rather than spur gear in transmission is





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MCQ->Advantages of helical gear rather than spur gear in transmission is....
MCQ-> The teaching and transmission of North Indian classical music is, and long has been, achieved by largely oral means. The raga and its structure, the often breathtaking intricacies of talc, or rhythm, and the incarnation of raga and tala as bandish or composition, are passed thus, between guru and shishya by word of mouth and direct demonstration, with no printed sheet of notated music, as it were, acting as a go-between. Saussure’s conception of language as a communication between addresser and addressee is given, in this model, a further instance, and a new, exotic complexity and glamour.These days, especially with the middle class having entered the domain of classical music and playing not a small part ensuring the continuation of this ancient tradition, the tape recorder serves as a handy technological slave and preserves, from oblivion, the vanishing, elusive moment of oral transmission. Hoary gurus, too, have seen the advantage of this device, and increasingly use it as an aid to instructing their pupils; in place of the shawls and other traditional objects that used to pass from shishya to guru in the past, as a token of the regard of the former for the latter, it is not unusual, today, to see cassettes changing hands.Part of my education in North Indian classical music was conducted via this rather ugly but beneficial rectangle of plastic, which I carried with me to England when I was a undergraduate. Once cassette had stored in it various talas played upon the tabla, at various tempos, by my music teacher’s brother-in law, Hazarilalii, who was a teacher of Kathak dance, as well as a singer and a tabla player. This was a work of great patience and prescience, a one-and-a-half hour performance without my immediate point or purpose, but intended for some delayed future moment who I’d practise the talas solitarily.This repeated playing our of the rhythmic cycles on the tabla was inflected by the noises-an hate auto driver blowing a horn; the sound bf overbearing pigeons that were such a nuisance on the banister; even the cry of a kulfi seller in summer —entering from the balcony of the third foot flat we occupied in those days, in a lane in a Bombay suburb, before we left the city for good. These sounds, in turn, would invade, hesitantly, the ebb and flow of silence inside the artificially heated room, in a borough of West London, in which I used to live as an undergraduate. There, in the trapped dust, silence and heat, the theka of the tabla, qualified by the imminent but intermittent presence of the Bombay subrub, would come to life again. A few years later, the tabla and, in the background, the pigeons and the itinerant kulfi seller, would inhabit a small graduate room in Oxford.cThe tape recorder, though, remains an extension of the oral transmission of music, rather than a replacement of it. And the oral transmission of North Indian classical music remains, almost uniquely, testament to the fact that the human brain can absorb, remember and reproduces structures of great complexity and sophistication without the help of the hieroglyph or written mark or a system of notation. I remember my surprise on discovering the Hazarilalji- who had mastered Kathak dance, tala and North Indian classical music, and who used to narrate to me, occasionally, compositions meant for dance that were grant and intricate in their verbal prosody, architecture and rhythmic complexity- was near illustrate and had barely learnt to write his name in large and clumsy letters.Of course, attempts have been made, throughout the 20th century, to formally codify and even notate this music, and institutions set up and degrees created, specifically to educate students in this “scientific” and codified manner. Paradoxically, however, this style of teaching has produced no noteworthy student or performer; the most creative musicians still emerge from the guru-shishya relationship, their understanding of music developed by oral communication.The fact that North Indian classical music emanates from, and has evolved through, oral culture, means that this music has a significantly different aesthetic, aw that this aesthetic has a different politics, from that of Western classical music) A piece of music in the Western tradition, at least in its most characteristic and popular conception, originates in its composer, and the connection between the two, between composer and the piece of music, is relatively unambiguous precisely because the composer writes down, in notation, his composition, as a poet might write down and publish his poem. However far the printed sheet of notated music might travel thus from the composer, it still remains his property; and the notion of property remains at the heart of the Western conception of “genius”, which derives from the Latin gignere or ‘to beget’.The genius in Western classical music is, then, the originator, begetter and owner of his work the printed, notated sheet testifying to his authority over his product and his power, not only of expression or imagination, but of origination. The conductor is a custodian and guardian of this property. IS it an accident that Mandelstam, in his notebooks, compares — celebratorily—the conductor’s baton to a policeman’s, saying all the music of the orchestra lies mute within it, waiting for its first movement to release it into the auditorium?The raga — transmitted through oral means — is, in a sense, no one’s property; it is not easy to pin down its source, or to know exactly where its provenance or origin lies. Unlike the Western classical tradition, where the composer begets his piece, notates it and stamps it with his ownership and remains, in effect, larger than, or the father of, his work, in the North India classical tradition, the raga — unconfined to a single incarnation, composer or performer — remains necessarily greater than the artiste who invokes it.This leads to a very different politics of interpretation and valuation, to an aesthetic that privileges the evanescent moment of performance and invocation over the controlling authority of genius and the permanent record. It is a tradition, thus, that would appear to value the performer, as medium, more highly than the composer who presumes to originate what, effectively, cannot be originated in a single person — because the raga is the inheritance of a culture.The author’s contention that the notion of property lies at the heart of the Western conception of genius is best indicated by which one of the following?
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MCQ->Two advantages of using helical gears rather than spur gears in a transmission system are....
MCQ-> In a modern computer, electronic and magnetic storage technologies play complementary roles. Electronic memory chips are fast but volatile (their contents are lost when the computer is unplugged). Magnetic tapes and hard disks are slower, but have the advantage that they are non-volatile, so that they can be used to store software and documents even when the power is off.In laboratories around the world, however, researchers are hoping to achieve the best of both worlds. They are trying to build magnetic memory chips that could be used in place of today’s electronics. These magnetic memories would be nonvolatile; but they would also he faster, would consume less power, and would be able to stand up to hazardous environments more easily. Such chips would have obvious applications in storage cards for digital cameras and music- players; they would enable handheld and laptop computers to boot up more quickly and to operate for longer; they would allow desktop computers to run faster; they would doubtless have military and space-faring advantages too. But although the theory behind them looks solid, there are tricky practical problems and need to be overcome.Two different approaches, based on different magnetic phenomena, are being pursued. The first, being investigated by Gary Prinz and his colleagues at the Naval Research Laboratory (NRL) in Washington, D.c), exploits the fact that the electrical resistance of some materials changes in the presence of magnetic field— a phenomenon known as magneto- resistance. For some multi-layered materials this effect is particularly powerful and is, accordingly, called “giant” magneto-resistance (GMR). Since 1997, the exploitation of GMR has made cheap multi-gigabyte hard disks commonplace. The magnetic orientations of the magnetised spots on the surface of a spinning disk are detected by measuring the changes they induce in the resistance of a tiny sensor. This technique is so sensitive that it means the spots can be made smaller and packed closer together than was previously possible, thus increasing the capacity and reducing the size and cost of a disk drive. Dr. Prinz and his colleagues are now exploiting the same phenomenon on the surface of memory chips, rather spinning disks. In a conventional memory chip, each binary digit (bit) of data is represented using a capacitor-reservoir of electrical charge that is either empty or fill -to represent a zero or a one. In the NRL’s magnetic design, by contrast, each bit is stored in a magnetic element in the form of a vertical pillar of magnetisable material. A matrix of wires passing above and below the elements allows each to be magnetised, either clockwise or anti-clockwise, to represent zero or one. Another set of wires allows current to pass through any particular element. By measuring an element’s resistance you can determine its magnetic orientation, and hence whether it is storing a zero or a one. Since the elements retain their magnetic orientation even when the power is off, the result is non-volatile memory. Unlike the elements of an electronic memory, a magnetic memory’s elements are not easily disrupted by radiation. And compared with electronic memories, whose capacitors need constant topping up, magnetic memories are simpler and consume less power. The NRL researchers plan to commercialise their device through a company called Non-V olatile Electronics, which recently began work on the necessary processing and fabrication techniques. But it will be some years before the first chips roll off the production line.Most attention in the field in focused on an alternative approach based on magnetic tunnel-junctions (MTJs), which are being investigated by researchers at chipmakers such as IBM, Motorola, Siemens and Hewlett-Packard. IBM’s research team, led by Stuart Parkin, has already created a 500-element working prototype that operates at 20 times the speed of conventional memory chips and consumes 1% of the power. Each element consists of a sandwich of two layers of magnetisable material separated by a barrier of aluminium oxide just four or five atoms thick. The polarisation of lower magnetisable layer is fixed in one direction, but that of the upper layer can be set (again, by passing a current through a matrix of control wires) either to the left or to the right, to store a zero or a one. The polarisations of the two layers are then either the same or opposite directions.Although the aluminum-oxide barrier is an electrical insulator, it is so thin that electrons are able to jump across it via a quantum-mechanical effect called tunnelling. It turns out that such tunnelling is easier when the two magnetic layers are polarised in the same direction than when they are polarised in opposite directions. So, by measuring the current that flows through the sandwich, it is possible to determine the alignment of the topmost layer, and hence whether it is storing a zero or a one.To build a full-scale memory chip based on MTJs is, however, no easy matter. According to Paulo Freitas, an expert on chip manufacturing at the Technical University of Lisbon, magnetic memory elements will have to become far smaller and more reliable than current prototypes if they are to compete with electronic memory. At the same time, they will have to be sensitive enough to respond when the appropriate wires in the control matrix are switched on, but not so sensitive that they respond when a neighbouring elements is changed. Despite these difficulties, the general consensus is that MTJs are the more promising ideas. Dr. Parkin says his group evaluated the GMR approach and decided not to pursue it, despite the fact that IBM pioneered GMR in hard disks. Dr. Prinz, however, contends that his plan will eventually offer higher storage densities and lower production costs.Not content with shaking up the multi-billion-dollar market for computer memory, some researchers have even more ambitious plans for magnetic computing. In a paper published last month in Science, Russell Cowburn and Mark Well and of Cambridge University outlined research that could form the basis of a magnetic microprocessor — a chip capable of manipulating (rather than merely storing) information magnetically. In place of conducting wires, a magnetic processor would have rows of magnetic dots, each of which could be polarised in one of two directions. Individual bits of information would travel down the rows as magnetic pulses, changing the orientation of the dots as they went. Dr. Cowbum and Dr. Welland have demonstrated how a logic gate (the basic element of a microprocessor) could work in such a scheme. In their experiment, they fed a signal in at one end of the chain of dots and used a second signal to control whether it propagated along the chain.It is, admittedly, a long way from a single logic gate to a full microprocessor, but this was true also when the transistor was first invented. Dr. Cowburn, who is now searching for backers to help commercialise the technology, says he believes it will be at least ten years before the first magnetic microprocessor is constructed. But other researchers in the field agree that such a chip, is the next logical step. Dr. Prinz says that once magnetic memory is sorted out “the target is to go after the logic circuits.” Whether all-magnetic computers will ever be able to compete with other contenders that are jostling to knock electronics off its perch — such as optical, biological and quantum computing — remains to be seen. Dr. Cowburn suggests that the future lies with hybrid machines that use different technologies. But computing with magnetism evidently has an attraction all its own.In developing magnetic memory chips to replace the electronic ones, two alternative research paths are being pursued. These are approaches based on:
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MCQ-> Analyse the following passage and provide appropriate answers that follow.We can answer Fermi’s Paradox in two ways. Perhaps our current science over - estimates the likelihood of extraterrestrial intelligence evolving. Or, perhaps, evolved technical intelligence has some deep tendency to be self - limiting, even self - exterminating. After Hiroshima, some suggested that any aliens bright enough to make colonizing space ships would be bright enough to make thermonuclear bombs, and would use them on each other sooner or later.I suggest a different, even darker solution to the Paradox. Basically, I think the aliens forget to send radio signals or colonize space because they’re too busy with runaway consumerism and virtual - reality narcissism. Once they turn inwards to chase their shiny pennies of pleasure, they lose the cosmic plot.The fundamental problem is that an evolved mind must pay attention to indirect cues of biological fitness, rather than tracking fitness itself. This was a key insight of evolutionary psychology in the early 1990s; although evolution favours brains that tend to maximize fitness (as measured by numbers of great - grandkids), no brain has capacity enough to do so under every possible circumstance. As a result, brains must evolve shortcuts: fitness - promoting tricks, cons, recipes and heuristics that work, on an average, under ancestrally normal conditions. Technology is fairly good at controlling external reality to promote real biological fitness, but it’s even better at delivering fake fitness - subjective cues of survival and reproduction without the real - world effects.Fitness - faking technology tends to evolve much faster than our psychological resistance to it. With the invention of Xbox 360, people would rather play a high - resolution virtual ape in Peter Jackson’s King Kong than be a perfect – resolution real human. Teens today must find their way through a carnival of addictively fitness - faking entertainment products. The traditional staples of physical, mental and social development - athletics, homework dating - are neglected. The few young people with the self - control to pursue the meritocratic path often get distracted at the last minute.Around 1900, most inventions concerned physical reality and in 2005 focus shifted to virtual entertainment. Freud’s pleasure principle triumphs over the reality principle. Today we narrow - cast human - interest stories to each other, rather than broadcasting messages of universal peace and progress to other star systems.Maybe the bright aliens did the same. I suspect that a certain period of fitness - faking narcissism is inevitable after any intelligent life evolves. This is the Great Temptation for any technological species – to shape their subjective reality to provide the cues of survival and reproductive success without the substance. Most bright alien species probably go extinct gradually, allocating more time and resources to their pleasures and less to their children.Heritable variation in personality might allow some lineages to resist the Great Temptation and last longer. Some individuals and families may start with an “irrational” Luddite abhorrence of entertainment technology, and they may evolve ever more self - control, conscientiousness and pragmatism by combining the family values of the religious right with the sustainability values of the Greenpeace. They wait patiently for our fitness - faking narcissism to go extinct. Those practical - minded breeders will inherit the Earth as like - minded aliens may have inherited a few other planets. When they finally achieve contacts, it will not be a meeting of novel - readers and game - players. It will be a meeting of dead - serious super - parents who congratulate each other on surviving not just the Bomb, but the Xbox.Among the following options, which one represents the most important concern raised in the passage?
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