Reboring of an engine cylinder to the next oversize would slightly ?->(Show Answer!)

1. Reboring of an engine cylinder to the next oversize would slightly

Answer: Increase the stroke volume

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MCQ-> Read the following passage carefully and answer the questions given below it. Certain words/phrases have been printed in bold to help you locate them while answering some of the questions. Once upon a time there was a King of Benaras who was very rich. He had many servants and a beautiful palace with wonderful gardens; he had chariots and a stable full of horses. But his most prized possession was a magnificent elephant called Mahaghiri. She was as tall as two men, and her skin was of the colour of thunder clouds. She had large flapping ears and small, bright eyes and she was very clever. Mahaghiri lived in her own special elephant house and had her own keeper, Rajinder. The King would often visit Mahaghiri to take her some special tit-bit to eat and check that Rajinder was looking after her properly. But Rajinder needed no reminding, for he also loved the elephant dearly, and trusted her completely. Every morning, he would take her down to the river for her bath. Then he would bring her freshly cut grass, leaves and the finest fruits he could find in the market for her breakfast. During the day, he would talk to her and, in the evening, he would play his flute to send her to sleep. One morning, Rajinder arrived as usual with fruit for Mahaghiri’s breakfast. Suddenly, before he knew what was happening, she picked him up with her trunk and threw him out of the stall, breaking his arm. She began to stamp on the ground and trumpet so loudly that it took several strong men all morning to bind her with ropes and chains, When the king heard about what had happened, he was very upset and sent for the doctor to help Rajinder. Then he called for his chief minister. “You must go and see Mahaghiri at once,” he said. “She used to be so kind and gentle, but this morning she threw her keeper out of her stall. I can’t understand it. She must be ill or in pain. Spare no expense in finding a cure.” So the chief minister went to see Mahaghiri. who was still bound firmly with ropes. First he looked at her eyes – they were as clear and bright as usual. Then he felt behind her ears – her temperature was normal. Next he listened to her heart that was fine too – and checked all over for cuts or sores. He could find nothing wrong with her. “Strange,” he thought. “I can find no explanation for her bad behaviour.”But then his eye was caught by something gleaming in the straw. It was a sharp, curved knife, like the ones used by robbers. Could there be a connection? That night, when everyone else had gone to bed, the chief minister returned to the elephant house. There, in the stall next to Mahaghiri’s, sat a band of robbers. “Tonight we’ll burgle the palace,” said the chief. “First, we’ll make a hole in the wall, then we’ll steal the treasure. “But what about the guards?” someone asked. “Don’t tell me you’re still afraid to kill! When will you learn to be a real robber?” From the shadows, the minister could see the elephant, her ears pinned back, listening to every hateful and violent word.”Just as I suspected,” thought the minister. Then he slipped out, bolted the door on the outside so the robbers could not escape, and went immediately to the king.”Your majesty,” he said, “I think I have found the cause of your elephant’s bad behaviour.” As soon as the king heard what the minister had to say, he sent for his guards and had the robbers arrested. “But what about the elephant? How can she be cured?’ he asked. “Well, your majesty, if Mahaghiri became dangerous through being.in the company of those wicked robbers, perhaps she could be cured by being in the company of good people.” “What a brilliant idea!” exclaimed the king. “Let us invite the friendliest, happiest and kindest people in the city to meet in the stall next to the elephant.” “Mahaghiri, the king’s most prized elephant, has been in bad company and has become violent and dangerous,” the minister told his friends. “Will you help her to become her old self again?””Of course,” they replied. “What do you want us to do?” “Just meet in the elephant house every day for the next week. Let her hear how kindly and thoughtfully you speak to each other, and how helpful you are.” So the minister’s friends met in the elephant house as planned. They talked together and enjoyed each other’s company. Sometimes they brought cakes and sweets to share; sometimes their children came and played happily in the straw. All the while, Mahaghiri watched and listened. Gradually, she became calmer. “I think it’s working,” said the minister. “Soon we’ll be able to remove the ropes.” Everyone felt a bit nervous when the day came for Mahaghiri to be untied. The king ordered everyone to wait outside as, very carefully, brave Rajinder began to undo the ropes around her ears and trunk. Next he removed the ropes holding her head. Finally, he loosened the thick chains holding her great feet. Everyone held their breath. What if she was still wild?Mahaghiri looked round shuffling her feet to stretch them. Then she slowly curled her trunk around her keeper’s waist and lifted him high into the air before placing him gently on her back. A great cheer went up. The king was delighted. “Let’s have a picnic to celebrate,” he announced. “Mahaghiri can come too.” What a great afternoon they all had! Mahaghiri bathed in the lake and gave the children rides. It seemed as though she had now become kinder, gentler and even more trustworthy than ever. But Rajinder never forgot what had happened and was always careful to set Mahaghiri a good example by being kind and friendly himself.As per the context of passage, what was the most prized possession of the king of Benaras ?
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MCQ-> Cells are the ultimate multi-taskers: they can switch on genes and carry out their orders, talk to each other, divide in two, and much more, all at the same time. But they couldn’t do any of these tricks without a power source to generate movement. The inside of a cell bustles with more traffic than Delhi roads, and, like all vehicles, the cell’s moving parts need engines. Physicists and biologists have looked ‘under the hood’ of the cell and laid out the nuts and bolts of molecular engines.The ability of such engines to convert chemical energy into motion is the envy nanotechnology researchers looking for ways to power molecule-sized devices. Medical researchers also want to understand how these engines work. Because these molecules are essential for cell division, scientists hope to shut down the rampant growth of cancer cells by deactivating certain motors. Improving motor-driven transport in nerve cells may also be helpful for treating diseases such as Alzheimer’s, Parkinson’s or ALS, also known as Lou Gehrig’s disease.We wouldn’t make it far in life without motor proteins. Our muscles wouldn’t contract. We couldn’t grow, because the growth process requires cells to duplicate their machinery and pull the copies apart. And our genes would be silent without the services of messenger RNA, which carries genetic instructions over to the cell’s protein-making factories. The movements that make these cellular activities possible occur along a complex network of threadlike fibers, or polymers, along which bundles of molecules travel like trams. The engines that power the cell’s freight are three families of proteins, called myosin, kinesin and dynein. For fuel, these proteins burn molecules of ATP, which cells make when they break down the carbohydrates and fats from the foods we eat. The energy from burning ATP causes changes in the proteins’ shape that allow them to heave themselves along the polymer track. The results are impressive: In one second, these molecules can travel between 50 and 100 times their own diameter. If a car with a five-foot-wide engine were as efficient, it would travel 170 to 340 kilometres per hour.Ronald Vale, a researcher at the Howard Hughes Medical Institute and the University of California at San Francisco, and Ronald Milligan of the Scripps Research Institute have realized a long-awaited goal by reconstructing the process by which myosin and kinesin move, almost down to the atom. The dynein motor, on the other hand, is still poorly understood. Myosin molecules, best known for their role in muscle contraction, form chains that lie between filaments of another protein called actin. Each myosin molecule has a tiny head that pokes out from the chain like oars from a canoe. Just as rowers propel their boat by stroking their oars through the water, the myosin molecules stick their heads into the actin and hoist themselves forward along the filament. While myosin moves along in short strokes, its cousin kinesin walks steadily along a different type of filament called a microtubule. Instead of using a projecting head as a lever, kinesin walks on two ‘legs’. Based on these differences, researchers used to think that myosin and kinesin were virtually unrelated. But newly discovered similarities in the motors’ ATP-processing machinery now suggest that they share a common ancestor — molecule. At this point, scientists can only speculate as to what type of primitive cell-like structure this ancestor occupied as it learned to burn ATP and use the energy to change shape. “We’ll never really know, because we can’t dig up the remains of ancient proteins, but that was probably a big evolutionary leap,” says Vale.On a slightly larger scale, loner cells like sperm or infectious bacteria are prime movers that resolutely push their way through to other cells. As L. Mahadevan and Paul Matsudaira of the Massachusetts Institute of Technology explain, the engines in this case are springs or ratchets that are clusters of molecules, rather than single proteins like myosin and kinesin. Researchers don’t yet fully understand these engines’ fueling process or the details of how they move, but the result is a force to be reckoned with. For example, one such engine is a spring-like stalk connecting a single-celled organism called a vorticellid to the leaf fragment it calls home. When exposed to calcium, the spring contracts, yanking the vorticellid down at speeds approaching three inches (eight centimetres) per second.Springs like this are coiled bundles of filaments that expand or contract in response to chemical cues. A wave of positively charged calcium ions, for example, neutralizes the negative charges that keep the filaments extended. Some sperm use spring-like engines made of actin filaments to shoot out a barb that penetrates the layers that surround an egg. And certain viruses use a similar apparatus to shoot their DNA into the host’s cell. Ratchets are also useful for moving whole cells, including some other sperm and pathogens. These engines are filaments that simply grow at one end, attracting chemical building blocks from nearby. Because the other end is anchored in place, the growing end pushes against any barrier that gets in its way.Both springs and ratchets are made up of small units that each move just slightly, but collectively produce a powerful movement. Ultimately, Mahadevan and Matsudaira hope to better understand just how these particles create an effect that seems to be so much more than the sum of its parts. Might such an understanding provide inspiration for ways to power artificial nano-sized devices in the future? “The short answer is absolutely,” says Mahadevan. “Biology has had a lot more time to evolve enormous richness in design for different organisms. Hopefully, studying these structures will not only improve our understanding of the biological world, it will also enable us to copy them, take apart their components and recreate them for other purpose.”According to the author, research on the power source of movement in cells can contribute to
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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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