材料力学论文

In the mid-1870s, French artist Frederic Auguste Bartholdi was working on an enormous project called Liberty Enlightening the World, a monument celebrating US independence and the France-America alliance. At the sametime, he was in love with a woman whom he had met in Canada. His mother could not approve of her son's affection for a woman she had never met, but Bartholdi went ahead and married his love in 1876.That same year Bartholdi had assembled the statue's right arm and torch, and displayed them in Philadelphia.It is said that he had used his wife's arm as the model, but felt her face was too beautiful for the statue. He needed someone whose face represented suffering yet strength, someone more severe than beautiful. He chose his mother.The Statue of Liberty was dedicated on an island in Upper New York Bay in 1886. It had his mother's face and his wife's body, but Bartholdi called it "my daughter, Liberty".BarbieBefore all the different types of Barbie dolls for sale now, there was just a single Barbie. Actually, her name was Barbara.Barbara Handler was the daughter of Elliot and Ruth Handler, co-founders of the Mattel T oy Company. Ruth came up with the idea for Barbie after watching her daughter play with paper dolls. The three-dimensional model for Barbie was a German doll—a joke gift for adults described as having the appearance of "a woman who sold sex". Mattel refashioned the doll into a decent, all-American—although with an exaggerated breast size—version and named it after Barbara, who was then a teenager.Since her introduction in 1959, Barbie has become the universally recognized Queen of the Dolls. Mattel says the average American girl owns ten Barbie dolls, and two are sold somewhere in the world every second.Now more than sixty years old, Barbara—who declines interviews but is said to have loved the doll—may be the most famous unknown figure on the planet.Barbie's boyfriend, Ken, was introduced in 1961 and named after Barbara's brother. The real Ken, who died in 1994, was disgusted by the doll that made his family famous. "I don't want my children to play with it," he said in 1993.American GothicGrant Wood instantly rose to fame in 1930 with his painting American Gothic, an often-copied interpretation of the solemn pride of American farmers. The painting shows a serious-looking man and a woman standing in front of a farmhouse. He was strongly influenced by medieval artists and inspired by the Gothic window of an old farmhouse, but the faces in his composition were what captured the world's attention.Wood liked to paint faces he knew well. For the grave farmer he used his dentist, a sour-looking man. For thewoman standing alongside him, the artist chose his sister, Nan. He stretched the models' necks a bit, but there was no doubt who posed for the portrait.Nan later remarked that the fame she gained from American Gothic saved her from a very boring life.The Buffalo NickelToday, American coins honor prominent figures of the US government—mostly famous former presidents. But the Buffalo nickel, produced from 1913 to 1938, honored a pair of connected tragedies from the settlement of the American frontier—the destruction of the buffalo herds and the American Indians.While white people had previously been used as models for most American coins, famed artist James Earle Fraser went against tradition by using three actual American Indians as models for his creation.For the buffalo on the other side, since buffalo no longer wandered about the great grasslands, Fraser was forced to sketch an aging buffalo from New York City's Central Park Zoo. Two years later, in 1915, this animal was sold for $100 and killed for meat, a hide, and a wall decoration made from its horns.Uncle SamFourteen-year-old Sam Wilson ran away from home to join his father and older brothers in the fight to liberate the American colonies from the British during the American Revolution. At age 23, he started a meat-packing business and earned a reputation for being honest and hard-working.During a later war in 1812, Wilson gained a position inspecting meat for US Army forces, working with a manwho had signed a contract with the government to provide meat to the army. Barrels of meat supplied to the army were stamped "EA-US", identifying the company (EA) and the country of origin (US). According to one story, when a government official visited the plant and asked about the letters, a creative employee told him "US" was short for "Uncle Sam" Wilson. Soon soldiers were saying all Army supplies were from "Uncle Sam".After the war, a character called Uncle Sam began appearing in political cartoons, his form evolving from an earlier cartoon character called Brother Jonathan that was popular during the American Revolution. Uncle Sam soon replaced Brother Jonathan as American's most popular symbol. The most enduring portrait of Uncle Sam was created by artist James Montgomery Flagg in his famous army recruiting posters of World Wars I and II. That version—a tall man with white hair and a small white beard on his chin, a dark blue coat and a tall hat with stars on it—was a self-portrait of Flagg.Ideally, people would like to know when an earthquake is going to happen and how bad it will be. In both Japan and China, people have long believed that earthquakes can be forecast. In Japan, scientists have wired the Earth and sea to detect movements. The Chinese have traditionally watched animals and plants for warning signs of earthquakes. For example, the Chinese have noted that before an earthquake, hens' behavior changes—they refuse to enter their cages at night. They have also noticed that snakes come out of the ground to freeze to death and that dogs bark a lot, even normally quiet dogs. Before the Hanshin earthquake in Japan, there were reports of large schools of fish swimming near the surface of the water. Certain birds, like pigeons, also seemed to be especially noisy and were reported to be flying in unusual patterns before the earthquake. Perhaps mostinteresting, and most easily measured, is a chemical change in ground water before a quake. Experimental data seem to indicate that the amount of radon (Rn) in the water under the surface of the Earth waxes before an earthquake.People would also like to be able to prevent the great destruction of property caused by earthquakes. After all,most of the people who die in earthquakes are killed by falling buildings. Therefore, building structures that can withstand the power of earthquakes is a major concern. Steel seems to be the best material, but not if it iswelded to form a rigid structure. Many new structures are built with a new type of steel joint, an I-joint, which appears to be the most durable type of joint. These joints of steel can move without breaking. Also, to prevent property damage, architects now design buildings so that the building's columns and horizontal beams are of equal strength, and vertical support columns are inserted deep into solid soil. In addition, many new houses have relatively light roofs and strong walls. Concrete pillars for highway bridges that previously only had steel rods inside are now enclosed in steel.Besides working to improve building structures, people in areas where earthquakes are common need toprepare for the possibility of a great earthquake. They should regularly check and reinforce their homes, place heavy objects in low positions, attach cupboards and cabinets to walls, and fasten doors so that they will not open accidentally during an earthquake.In addition to preparing their houses, people in these regions need to prepare themselves. They should have supplies of water and food at home and at work. It is best to store several gallons of water per person. It is also important to have something that can clean water and kill bacteria, so water from other sources can be madesafe to drink. Store one week's food for each person. Earthquake survival supplies include a radio receiver, a torch, extra batteries, first aid supplies, a spade, a tent, some rope, and warm clothing. Experts also suggest the following:Keep a fire extinguisher handy. You should have one at home, at work, and in your car (if you have one). The fire extinguisher should be able to put out any type of fire. Have the proper tools to turn off gas and water lines if necessary. Arrange an auxiliary cooking and heating source that can be used outside. One alternative is a portable camp stove with small cans of gas. Keep a pair of heavy, comfortable shoes or boots in your home, at work, and in your vehicle. If there is an earthquake, there will be lots of fragments of broken glass. Light shoes will not protect your feet as well as heavy shoes will.Every family needs to have earthquake emergency plans. How will family members leave the area during the chaos following an earthquake? Everyone should agree on a meeting point outside of the area—perhaps in atown several miles away. Also important is an arrangement for family members to communicate if there is an earthquake. If an earthquake happens in a large city, many of the telephone lines within the city are likely to be down. The few remaining working lines will be busy with the calls that naturally occur after a disaster and it will be difficult to call from one part of the city to another. It might, however, be possible to call outside the city.A sensible arrangement is to have all of the members of the family call to check in with a friend or relative who lives more than a hundred miles away.Although scientists still cannot predict earthquakes, they are learning a great deal about how the large plates in the Earth's crust move, the stresses between plates, how earthquakes work, and the general probability that agiven place will have an earthquake. Someday soon it may actually become possible to predict earthquakes with accuracy. However, even if prediction becomes possible, people who live in areas where earthquakes are a common occurrence will still have to do their best to prevent disasters by building structures that are resistant to ground movement and by being personally prepared. These precautions can make a great difference in saving lives and preventing the loss of homes. Education concerning how to survive an earthquake should be a major emphasis for all government programs and earthquake-related research projects.John Bullyer and I met for the first time when we were both in our early sixties, but it is true to say that he did more to shape my life than any other person, and is largely responsible for the shyness which has been a handicap to me.Aunt Carrie was my favorite relative, as well as my favorite authority figure. She was always free with smiles,words of praise, and excuses for misdoings. For me she had but one drawback: She was also aunt to JohnBullyer, the son of her sister who lived in Gloucestershire. She invariably referred to him as "Little-John-my-other-nephew" all in one word, and she referred to him far too often.Probably hundreds of comparisons were made before I became aware of them. The first that I remember with any clarity was that Little-John-Aunt-Carrie's-other-nephew had started school on the same day as I did and had taken to it like a duck to water. My first day, on the other hand, was disastrous.And so it went on. Incredible boy, he advanced quickly in mathematics; he was dealing expertly with advanced math, just cruising through, while I was practically slamming my head against a wall trying to learn percentages.I began to dread Aunt Carrie's visits, because she was always comparing the two of us.Time went on; so did the comparisons. By word of mouth during the holidays, by phrases that leaped out of letters during term time, I was kept up to date with John's progress. Thus challenged, I began at last to lookround for something that I could do well. When I discovered that I could write well, I worked with intensity at my craft, minding nothing else. Let this be mine, John Bullyer could have all the rest.The stories that I invented were mostly technological and science fiction in nature. They told of rockets andspacecraft, things that would take men high up into the sky. After some analysis of my personality, I realized that my stories were an extension of my own desires to rise to higher and higher altitudes, until I was above John Bullyer.Three or four times during the next forty years I saw mention of John Bullyer in the press. He was doingmathematical work that supported big, scientific projects. It was not the kind of career to attract much publicity, but occasional paragraphs in newspapers charted a steady success until he retired. On that occasion there was a half column about him; it said that his last job was the harnessing of solar power for a satellite put into orbit. He was working for a government bureau in a country in the Persian Gulf. I was, by that time, successful in my own line, having written a streak of 30 best-sellers without a single failure.Late that year, in November, I was in a club, sipping a glass of wine before dinner. A cough made me look round.I saw a short, fat man with a little nose that looked too small to support the framework of his heavy glasses.With more than a suggestion of discomfort, he spoke my name and I, somewhat reluctantly, admitted myidentity. Since I attained some measures of fame I have on occasion been approached by strangers. Whatever they say, I am always horribly embarrassed."You d-don't know m-me," said the little man, stammering. "My name's John B-Bullyer. We sh-shared an aunt, C-Caroline Lacey. I used to hear so much about you," he said with a smile. "You see... I grew up with the idea that you were at least eight feet tall, handsome, dynamic, and more able than anyone in the universe." His smile broadened. "Really," he said, "the letters Aunt Carrie used to write about you almost drove me to suicide. I grew to hate the sound of your name at times.""Those letters were probably nothing," I said, surprised to meet this man after so many years of having heard of him, "compared to the letters your mother used to write about you. I was told every time you got a sum right.I always thought of you as an imposing specimen of a man—nine feet high, better looking than Robert T aylor and wiser than Churchill. So they played the game both ways, did they?""But it was worse for me," he said. "I've always been undersized, and I always had these." He touched his glasses. "And there you were, tall and handsome. And so clever too. I had to do something; and all I could ever do was sums, and nearly killed myself at games in an effort to be liked by others. I might almost say," he said, with something like resentment, "that because of you I've been doing sums all my life!""Substitute writing stories for doing sums and you have exactly my story," I said.We looked at each other with identical expressions. Then it probably dawned on us both that the place in which we sat is not the place of men who have been failures in life, and that for boys, being what they are, an occasional push is not such a bad thing. Together we lifted our glasses, and the tensions between us went away. And though neither of us spoke, I know we drank to the memory of our Aunt Carrie。