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炉前混氢和炉后区别是什么? 炉前混氢和炉后区别是什么?炉前和炉后使用如何选择? 查看更多 3个回答 . 3人已关注
中小煤企成神华价格战“炮灰”? 本文由 盖德化工论坛转载自互联网 近日,作为 煤炭 市场风向标的神华集团一个月内七次降价,煤价跌至2007年以来的最低位。 一位煤炭行业人士,神华再次下调结算价格后,其他几家煤企相关人士初步表示,继续跟进,价格战愈演愈烈。 而在产能过剩和价格战的影响下,煤炭企业的寒冬仍在继续,目前整个行业的亏损面已经超过了70%以上。 神华“七连降” 7月28日,国内煤企龙头神华集团再次下调煤价10元/吨,这是该公司自6月26日以来第七次下调煤价。 这也导致了国内动力煤5500大卡北方港口平仓价已降到475元/吨,跌至2007年以来的最低位。 据悉,神华集团此次主要针对大客户群体进行降价,其目的是增加煤炭销售量。 在6月下旬神华降价之前,煤炭市场已经风声鹤唳,北方各大港口库存大幅飙升、“煤满为患”,秦皇岛港煤炭库存从500多万吨升至726万吨;神华旗下的黄骅港的煤炭库存也从5月底167万吨飙升至260万吨,出现压港情况,神华已经要求部分电企派船北上协助疏港。 与此同时,神华上半年的产销量都有所下滑。 根据其公布的数据,今年前6个月中国神华商品煤产量为1.55亿吨,同比下降2.1%;商品煤销售量2.346亿吨,同比下降3.3%。 这样的情况在神华的历史上并不多见,在2011年-2013年煤价持续下跌的情况下,神华的煤炭产量依然保持高速增长。 根据数据,神华2011—2013年的煤炭产量分别为2.82亿吨、4.4亿吨和4.98亿吨,其中2013年比2011年增加近8成。 销售不畅、库存压港,于是煤老大开启了这一轮降价潮。 6月25日,神华集团宣布降价,其中,5800和5500大卡大幅下调20元/吨至510元/吨,5200大卡下调15元/吨,5000大卡以下下调10元/吨。 在此之后,神华又连续6次下调煤价,而降价的效果显而易见。 自神华多次调价之后,其旗下黄骅港的煤炭库存从6月下旬最高的260万吨,快速下降至7月28日的163万吨,恢复到正常的库存水平。 在神华“七连降”的同时,环渤海动力煤价格指数也连续八周下降,跌破“500”整数大关,收于498元/吨,刷新了该指数自2010年10月13日发布以来的最低记录。 虽然煤市的大萧条已经持续了多年,但行业人士对后市依然不乐观。 “煤价是否企稳还要看进口煤的价格,不过进口煤价格下来的可能性还是比较低。”煤炭专家李朝林表示。 与此同时,煤炭行业的产能过剩是个大问题。据悉,2013年全国煤炭产量是37亿吨,今年估计在38亿吨左右,过剩达5亿吨。而截至4月末,全社会煤炭库存已经连续29个月在3亿吨以上。 一位不愿具名的煤炭行业分析师表示,“现在市场上5500大卡实际成交价格在475左右,有个别低价已经低至470附近,这表明市场还在继续下行,还没有到探底的时候。” 申银万国在研报中表示,“目前,尚未看到产能去化信号,在GDP增速放缓以及能源结构调整的大背景下,煤炭行业的寒冬仍将继续。” 7月中旬,煤炭工业协会召集晋陕蒙三大产煤省区和大型煤炭企业召开会议,会上呼吁各大煤企控制产量,降低库存。 一个好的信号是作为行业老大,神华已经率先做出响应。神华集团副总经理兼神华销售集团公司董事长王金力日前宣布,神华全年将调减煤炭产量5000万吨、调减煤炭销售量6000万吨。 中小煤企成“炮灰” 作为国内最大的煤炭企业,神华2013年的煤炭产量近5亿吨,而第二名中煤能源的数据还不到1.2亿吨,神华的调价策略直接影响了中国整个煤炭行业的价格走势。 为了争夺有限的市场份额,价格战一触即发。 在神华本轮“7连降”之后,中煤也进行了6轮调价,而在去年,两巨头也曾大打价格战,当时动力煤的价格也是连跌八周。 目前整个行业已经进入到了一个降价的死循环。“神华有最低价承诺,中煤跟进,神华就再次下调价格,中煤再跟进,神华再次降价……”上述煤炭分析人士表示。 在神华、中煤两巨头的较量中,中小煤企则不幸沦为“炮灰”。 某煤炭大省的一位官员就曾对神华的高层抱怨:“你们神华带头连续下调煤价,全国煤炭企业苦不堪言,我们省的煤炭企业日子都快过不下去了。” 在外界看来,仅从经营的角度来看,神华是没有必要执行如此高频率的降价策略的。 煤炭板块,神华已经打通了全产业链,形成了以煤为基础,电力、铁路、港口、航运、 煤化工 的一体化经营;运输板块,神华更是垄断了国内主要的几条煤炭运输线路,并拥有黄骅港、天津煤码头、珠海煤码头等三个港口,产业链优势明显。 在其他煤企都在为微利苦苦挣扎时,神华2013年仍然实现了456亿元的净利润。 面对这些质疑,神华新闻发言人孟坚也做出了解释:“神华此番煤价调整,完全是顺市而为、顺势而为。” 他认为,神华虽然是全国最大的煤炭企业,但煤炭市场份额仅占全国煤炭市场的7%左右,根本不可能左右、甚至影响煤炭市场价格。 “在强大的市场面前,神华能做的就是‘随行就市’,否则只能是死路一条!”孟坚表示。 而煤炭企业亏损面则在继续扩大,今年以来,中小型煤企迎来了新一轮的停产潮。 中国煤炭工业协会会长王显政表示,煤炭企业的亏损面已经超过了70%以上。 “因为煤炭企业亏损严重,目前已有50%以上的企业职工工资下滑,部分企业出现了缓发、减发、欠发工资的现象。”王显政表示。 截至7月底,已有20家煤企发布了上半年业绩预告,有15家煤企净利润同比下降,其中8家煤企净利润亏损。查看更多 0个回答 . 4人已关注
闪蒸系统各液位的控制? 对于闪蒸系统来说液位一般控制多少有利于操作,而且又能保证闪蒸的效果呢。查看更多 6个回答 . 2人已关注
2012年4月职称英语理工A试卷真题及答案完整版? 2012职称英语理工A试卷   一、词汇选项:    1.We almost ran into a Rolls-Royce that pulled out in front of us withoutsignaling.   A. overtook    B. hit   C. passed   D. found   2.He shifted his position a little, in order to alleviate the pain in hisleg.   A. control    B. ease   C. experience   D. suffer   3.Our aim was to update the health service, and we succeeded.   A. offer   B. provide   C. fund    D. modernize   4.Every week the magazine presents the profile of a well-known sportspersonality.    A. description   B. success   C. evidence   D. plan   5.All the flats in the building had the same layout .   A. color   B. size   C. function    D. arrangement   6.Newborn babies can discriminate between a man’s and a woman’s voice.   A. treat   B. express    C. distinguish   D. analyze   7.The weather was crisp and clear and you could see the mountains fiftymiles away.   A. hot   B. heavy    C. fresh   D. windy   8.Nothing would induce me to vote for him again.   A. teach   B. help    C. attract   D. discourage   9.When I heard the noise in the next room, I couldn’t resist have a peep .   A. chance    B. look   C.visit   D. try   10.Her comments about men are utterly ridiculous.   A. slightly   B. partly   C. faintly    D. completely   11.He was weary of the constant battle between them.   A. fond   B. proud    C. tired   D. afraid   12.She moves from one exotic location to another.    A. unusual   B. familiar   C. similar   D. proper   13.He has been granted asylum in France.    A. protection   B. power   C.relief   D. license   14.The photographs evoked memories of our   A. stored   B. blocked   C.erased    D. refreshed   15.The walls are made of hollow concrete blocks.    A. empty   B.big   C. long   D. new   二、阅读判断 Europa’swatery underworld   Europa, one of Jupiter’s 63 known moons,looks bright and icy on the surface. But appearances can be deceiving: Mileswithin its cracked, frigid shell, Europa probably hides giant pools of liquidwater. Where scientists find liquid water, they hope to find life as well.   Since we can’t go diving into Europa’sdepths just yet, scientists instead have to investigate the moon’s surface forclues to what lies beneath. In a new study, scientists investigated one groupof strange ice patterns on Europa and concluded that the formations mark thetop of an underground pool that holds as much water as the U.S. Great Lakes.   Pictures of Europa, which is slightlysmaller than Earth’s moon, clearly show a tangled, icy mishmash of lines andcracks known as “chaos terrains.” These chaotic places cover more than half ofEuropa. For more than 10 years, scientists have wondered what causes theformations. The new study suggests that they arise from the mixing of vastunderground stores of liquid water with icy material near the surface.   For scientists who suspect that Europaalso may be hiding life beneath its icy surface, the news about the new lake i**citing.   “It would be great if these lakesharbored life,” Britney Schmidt, a planetary scientist who worked on the study,told Science News. “But even if they didn’t, they say that Europa is doingsomething interesting and active right now.”   Schmidt, a scientist at the University of Texas at Austin, and her colleagueswanted to know how chaos terrains form. Since they couldn’t rocket to Europa tosee for themselves, they searched for similar formations here on Earth. Theystudied collapsed ice shelves in Antarctica and icy caps on volcanoes in Iceland. Thosefeatures on Earth formed when liquid water mixed with ice. The scientists nowsuspect something similar might be happening on Europa: that as water and iceof different temperatures mingle and shift, the surface fractures. This wouldexplain the jumbled ice sculptures.   “Fracturing catastrophically disruptsthe ice in the same way that it causes ice shelves to collapse on Earth,”Schmidt told Science News. She and her team found that the process could becausing chaos terrains to form quickly on Europa.   The new study suggests that on thismoon, elements such as oxygen from the surface blend with the deep bodies ofwater. That mixture may create an environment that supports life.    16.The liquid water of an underground pool of Europa is estimated xxxxx of the US Greatlakes.    A. Right   B. Wrong   C. Not mention   17.The strange ice patterns on Europa are formed as a result of a xxxxx undergroundwater pool.   A. Right    B. Wrong   C. Not mention   18.Europa is the most recently discovered one among Jupiter’s   A. Right   B. Wrong    C. Notmention   19.The size of Europa is a bit larger than that of Earth’s moon.   A. Right    B. Wrong   C. Not mention   20.Schmidt and her colleagues are the first group of scientists xxxxx Europa.   A. Right    B. Wrong   C. Not mention   21.The formations on Europa’s surface are rather unique in the   A. Right    B. Wrong   C. Not mention   22.The existence of liquid water is a necessity for a life-support    A. Right   B. Wrong   C. Not mention   三、概括大意与完成句子 Learnabout Noble Gases(惰性气体)   1 Have you ever ridden on a balloon? Many tourist spots offer balloon rides inorder for people to see the beauty of a place from above. A balloon contains anoble gas called helium(氦). Formerly, balloons contained hydrogenbut hydrogen is very flammable and dangerous when uncontrolled. Therefore, peopleshifted to helium, which is safer. Helium is safe because it has the propertiesof the noble gases.   2 People once believed that noble gases couldn’t chemically react at all. Forthis reason, they were called inert gases(惰性气体). They werealso listed under Group 0 in theold periodic table because scientists believed that the gases have zero valence(价)electrons in their outer shell. This was later proven to be untrue when somenoble gas compounds were discovered.   3  Thegases are elements, which share similar properties. These properties includebeing monoatomic, colorless, odorless, being able to conduct electricity, andhaving low chemical reactivity. Noble gases include Helium, Neon, Argon,Krypton, Xenon and Radon. These are all found in Group 18, in the rightmostcolumn of the periodic table. If you look at the periodic table, you willnotice that these elements are the only ones, which do not have a charge.Helium has the lowest molecular(分子的) weight whileRadon is the heaviest.   4  Remember that chemical reactions occurbecause atoms have valence electrons, which are electrons in their outer shell.When the outer shell is “unfilled” or the required number of electrons is notyet complete, the atom is more reactive. Noble gases have a full outer shell,meaning that they have complete electrons in their outer shell. This completenumber varies. For instance, the outer shell of Helium has 2 valence electronswhile the outer shell of Xenon has 8 electrons. Nowadays, there remains to be afew noble gases because of the low chemical reactivity of these said gases.   A. what is theperiodic table?   B. What are noblegases?   C. What causes the lowchemical reactivity of noble gases?   D. How were noblegases discovered?   E. How were noblegases understood in the past?   F. what are theapplications of noble gases?   5because of their properties, noble gases have many importantapplications. They are widely used in medicine and industries. For instance,liquid Helium is used for superconducting magnets( 磁体 ).These magnets are very important in physics and medicine. When a doctorsuspects that a person’s brain has been damaged, he might request for MagneticResonance Imaging(MRI). MRI allows the doctor to “see” the brain, withoutoperating on the patient.   23.paragraph 2__ E ___   24.paragraph 3__ B ____   25.paragraph 4___ C ____   26.paragraph 5___ F _____   27.Noble gases are not very chemically A   28.Among the elements of noble gases Helium is the B   29.The required number of electrons in noble gases’ outer shell is D   30.MRI may make operating on the patient F   A. reactive   B. lightest   C. important   D. complete   E. flammable   F. unnecessary   四、阅读理解    第一篇   Gross NationalHappiness   In the last century, new technologyimproved the lives of many people in many countries. However, one countryresisted these changes. High in the Himalayan mountains of Asia, the kingdom of Bhutan remained separate. Its people andBuddhist(佛教)culture had not been affected for almost a thousand years. Bhutan,however, was a poor country. People died at a young age. Most of its peoplecould not read, and they did not know much about the outside world. Then, in 1972,a new ruler named King Jigme Singye Wangchuck decided to help Bhutan tobecome modern, but without losing its traditions.   King Wangchuck looked at other countriesfor ideas. He saw that most countries measured their progress by their GrossNational Product (GNP). The GNP measures products and money. When the number ofproducts sold increases, people say the country is making progress. KingWangchuck had a different idea for Bhutan. He wanted to measure hiscountry’s progress by people’s happiness. If the people’s happiness increased,the king could say that Bhutanwas making progress. To decide if people were happier, he created a measurecalled Gross National Happiness (GNH).   GNH is based on certain principles thatcreate happiness. People are happier if they have health care, education, andjobs. They are happier when they live in a healthy, protected environment. Theyare happier when they can keep their traditional culture and customs. Finally,people are happier when they have a good, stable **.   Now there is some evidence of increasedGNH in Bhutan.People are healthier and are living longer. More people are educated andemployed. Teenty-five percent of the land has become national parks, and thecountry has almost no pollution. The Bhutanese continue to wear theirtraditional clothing and follow their ancient Buddhist customs. Bhutan has alsobecome a democracy. In 2008, King Wangchuck gave his power to his son. Althoughthe country still had a king, it held its first democratic elections that year.Bhutanhad political parties and political candidates for the first time. Finally, Bhutan hasconnected to the rest of the world through television and internet.   Bhutanis a symbol for social progress. Many countries are now interested in Bhutan’s GNH.These countries are investigating their own ways to measure happiness. Theywant to create new policies that take care of their people, cultures, and land.   Brazilmay be the nest country to use the principles of GNH. Brazilian leaders see theprinciples of GNH as a source of inspiration. Brazil is a large country with adiverse population. If happiness works as a measure of progress in Brazil, perhapsthe rest of the world will follow.   31.Who was Jigme Singye Wangchuck?   A. Apresident.   B. A Buddhistpriest.    C. A king .   D. A general.   32.Apart from modernizing Bhutan,what else did Wangchuck want to do for Bhutan?   A. To make itspopulation grow.   B. To keep itseparate from the world.    C. To keep its traditions and customs .   D. To encourageits people to get rich.   33.A country shows its progress with GNP by    A. selling more products .   B. spending moremoney.   C. spending lessmoney.   D. providingmore jobs.   34.According to GNH, people are happier if they   A. have newtechnology.    B. have a good, stable ** .   C. can changetheir religion.   D. have moremoney.   35.Today many countries are   A. using theprinciples of GNH to measure their progress.   B. workingtogether to develop a common scale to measure GNH.   C. taking both Bhutan and Brazil as symbols for socialprogress.    D. trying to find their own ways tomeasure happiness .    第二篇    DownloadKnowledge Directly to Your Brain   For the first time, researchers havebeen able to hack into the process of learning in the brain, using inducedbrain patterns to create a learned behavior. It’s not quite as advanced as aninstant kung-fu download, and it’s not as sleek as cognitive inception, butit’s still an important finding that could lead to new teaching andrehabilitation techniques.   Future therapies could decode the brainactivity patterns of an athlete or a musician, and use them as a benchmark forteaching another person a new activity, according to the researchers.   Scientists from BostonUniversity and ATR ComputationalNeuroscience Laboratories in Kyotoused functional magnetic resonance imaging, or fMRI, to study the learningprocess. They were examining the adult brain’s aptitude for visual perceptuallearning, or VPL, in which repetitive training improves a person’s performanceon a particular task. Whether adults can do this as well as young people hasbeen an ongoing debate in neuroscience.   Led by BU neuroscientist Takeo Watanabe,researchers used a method called decoded fMRI neurofeedback to stimulate thevisual cortex. First they showed participants circles at differentorientations. Then they used fMRI to watch the participants’ brain activity.The researchers were then able to train the participants to recreate thisvisual cortex activity.   The volunteers were again placed in MRImachines and asked to visualize shapes of certain colors. The participants wereasked to “somehow regulate activity in the posterior part of the brain” to makea solid green disc as large as they could. They were told they would get a paidbonus proportional to the size of this disc, but they weren’t told anythingabout what the disc meant. The researchers watched the participants’ brainactivity and monitored the activation patterns in their visual cortices.   “Participants can be trained to control theoverall mean activation of an entire brain region,” the study authors write,“or the activation in one region relative to that in another region.”   This worked even when test subjects werenot aware of what they were learning, the researchers said.   “The most surprising thing in this study isthat mere inductions of neural activation patterns corresponding to a specificvisual feature led to visual performance improvement on the visual feature,without presenting the feature or subjects'''' awareness of what was to be learned,”Watanabe said in a statement.   Watanabe and colleagues said this methodcan be a powerful tool.   “It can ‘incept’ a person to acquire newlearning, skills, or memory, or possibly to restore skills or knowledge thathas been damaged through accident, disease, or aging, without a person’sawareness of what is learned or memorized,” they write.   36. what have researchers been ableto do with the help of the study?    A. Discover aperson’s learning process in the brain .   B. Make a person know how to do something without learning.   C. Set up different learning patterns for different people.   D. Enable people to learn kung fu instantly.   37. what helps aperson to do a particular task better in visual perceptual learning?   A. Testing   B. Encouragement   C. Self- assessment    D. Repetition   38. which of thefollowing statements is true of the experiment participants?   A.They learned how to control MRL machines in the experiment    B. They werenot told what to be learned in the experiment   C.They were paid to take part in the experiment   D.They were not cooperative in the experiment   39. the findingof the study is most significant in that learning   A. is full offun    B. is visualized   C. happens unconsciously   D. becomes unnecessary   40. who are mostlikely to benefit from the study?   A. Teenagers   B. Musicians    C. Senior people   D. Athletes    第三篇    Small But Wise   On December 14, NASA1 blasted a smallbut mighty telescope into space. The telescope is called WISE and is about aswide around as a trashcan. Don''''t let its small size fool you: WISE has apowerful digital camera, and it will be taking pictures of some the wildestobjects2 in the known universe,including asteroids, faint stars, blazing galaxies3 and giant clouds of dustwhere planets and stars are born.   “I''''mvery excited because we''''re going to be seeing parts of the universe that wehaven''''t seen before, ” said Ned Wright, a scientist who directs the WISEproject.   Since arriving in space, the WISEtelescope has been circling the Earth, held by gravity in a polar orbit4( thismeans it crosses close to the north and south poles with each lap5). Its camerais pointed outward, away from the Earth, and WISE will snap a picture of adifferent part of the sky every 11 minutes. After six months it will have takenpictures across the entire sky.   The pictures taken by WISE won''''t be likeeveryday digital photographs, however. WISE stands for “Wide-field InfraredSurvey Explorer. ” As its name suggests, the WISE camera takes pictures offeatures that give off infrared radiation6.   Radiation is energy that travels as awave. Visible light, including the familiar spectrum of light7 that becomesvisible in a rainbow, is an example of radiation. When an ordinary digitalcamera takes a picture of a tree, for example, it receives the waves of visiblelight that are reflected off the tree. When these waves enter the camerathrough the lens, they''''re processed by the camera, which then puts the imagetogether.   Waves of infrared radiation are longerthan waves of visible light, so ordinary digital cameras don''''t see them, andneither do the eyes of human beings. Although invisible to the eye, longerinfrared radiation can be detected as warmth by the skin.   That''''s a key idea to why WISE will beable to see things other telescopes can''''t. Not everything in the universe showsup in visible light. Asteroids, for example, are giant rocks that float throughspace — but they absorb most of the light that reaches them. They don''''t reflectlight, so they''''re difficult to see. But they do give off infrared radiation, soan infrared telescope like WISE will be able to produce images of them. Duringits mission WISE will take pictures of hundreds of thousands of asteroids.   Brown dwarfs8 are another kind ofdeep-space object that will show up in WISE''''s pictures. These objects are“failed” stars — which means they are not massive enough to jump start9 thesame kind of reactions that power stars such as the sun. Instead, brown dwarfssimply shrink and cool down. They''''re so dim that they''''re almost impossible tosee with visible light, but in the infrared spectrum they glow.   41. What is sospecial about WISE?   A It is as small as a trashcan.   B It is small in size but carries a large camera.    C Its digital camera can helpastronomers to see the unknown space .   D Never before has a telescope carried a digital camera in space.   42. The cameraon WISE   A is equipped with expensive computers.    B produces images of objects givingoff infrared radiation .   C reflects light visible to the human eyes.   D is similar to an ordinary digital camera.   43. It is truethat infrared radiation.   A is not detectable to humans.   B looks brighter than visible light.   C is visible light reflected off an object.    D has longer waves than thoseof visible light .   44. Which of thefollowing statements about asteroids is NOT ture?   A The WISE telescope can catch and take pictures of them.   B They do not reflect light that reaches them.    C They float through spacegiving off visible light .   D They are invisible to ordinary cameras.   45. It can beinferred from the last paragraph that brown dwarfs.    A give off infrared radiation .   B are power stars like the sun.   C become massive and active   D are invisible to the WISE telescope.   五、补全短文 The Mysteries of Nazca   In the desert of Peru, 300 kilometersfrom Lima, one of the most unusual artworks in the world has mystified (迷惑)people for decades. F (46) But from high above, these marks are hugeimages of birds, fish, seashells, all beautifully carved into the earth.   TheNazca lines are so difficult to see from the ground that they weren’tdiscovered until the 1930s, when pilots spotted them while flying over thearea. In all, there are about 70 different human and animal figures on theplain, along with 900 triangles, circles, and lines.   Researchershave figured out that the lines are at least 1,500 years old, but their purposeis still a mystery. D (47) However, it would probably be very trickyto xxxxx and a spaceship in the middle ofpictures of dogs and monkeys.   Inthe 1940s, an American explorer named Paul Kosok suggested that the drawingsare a chronicle (记录) of the movement ofthe stars and planets. C (48) xxxxx anastronomer tested his theory with a computer, but he couldn’t find any relationbetween the lines and movements in space.   Anotherexplanation is that the lines may have been made for religious reasons. xxxxx researcher Tony Morrison investigated thecustoms of people in the Andes xxxxx and learned that they sometimes pray by the sideof the road. It’s possible that xxxxx, the linesof Nazca were created for a similar purpose. B (49) But xxxxxpeople have never constructed anything this big.   Recently,two other scientists, David Johnson and Steve Mabee, have speculated xxxxx lines could have been related to water. Nazca isone of the driest places in the xxxxx receivesonly 2cm of rain every year.While Johnson was searching for xxxxx watersources in the area, he noticed that some waterways built ancient xxxxx were connected with the lines. Johnson believesthat the Nazca lines are a giant xxxxxunderground water in the area. E (50)   A.. Scholars differ in interpretingthe purpose of the designs.   B. The largestpicture may have been the sites for special ceremonies.   C. He calledNazca “the largest astronomy book in the world”   D. A Swisswriter named Erich von Daniken wrote that the Nazca lines were designed as alanding place for UFOs.   E. Otherscientists are now searching for evidence to prove this.   F. Seen from theground, it looks like lines scratched into the earth.   六、完型填空 Solar Power without Solar Cells   A dramatic and surprising magneticeffect of light discovered by University of Michigan1researcherscould lead to solar power without traditional semiconductor-based solar cells.   The researchers found a way to make an“optical  51  ,” said Stephen Rand, a professor in thedepartments of Electrical Engineering and Computer Science, Physics and AppliedPhysics.   Light has electric and magnetic  52  .Until now, scientists thought the effect of the magnetic field were so weakthat they could be   53  . What Rand and his colleagues found isthat at the right intensity, when light is traveling through a material thatdoes not   54  electricity, the light field cangenerate magnetic effects that are 100 million times stronger than previouslyexpected. Under these circumstances, the magnetic effects develop strength  55  toa strong electric effect.   “This could lead to a new kind of solarcell without semiconductors and without absorption to produce charge separation,” Rand said. “In solar cells, the   56  goesinto a material, gets absorbed and creates heat. Here, we expect to have a verylow heat load2. Instead of the light being absorbed, energy is stored in themagnetic moment3. Intense magnetization can be induced by intense light andthen it is ultimately capable of providing a capacitive power   57  Whatmakes this possible is a previously undetected brand of “opticalrectification,” says William Fisher, a doctoral student in applied physics. Intraditional optical rectification, light''''s electric field causes a chargeseparation, or a pulling  58  of the positive and negative charges ina material. This sets up a voltage, similar to  59  in a battery.   Rand and Fisher found that under the rightcircumstances and in right types of materials, the light''''s magnetic field canalso create optical rectification. The light must be shone through  a   60  thatdoes not conduct electricity, such as glass. And it must be focused to anintensity of 10 million watts per square centimeter8. Sunlight isn''''t this  61  onits own, but new materials are being sought that would work at lowerintensities, Fisher said.   “In our most recent paper, we show thatincoherent light9 like sunlight is theoretically almost  62  effectivein producing charge separation as laser light is,” Fisher said.   This new  63  couldmake solar power cheaper, the researchers say. They predict that with improvedmaterials they could achieve 10 percent efficiency in converting solar power touseable energy. That''''s equivalent to today''''s commercial-grade solar cells.   “To manufacture modem solar cells, youhave to do  64  semiconductor processing,” Fisher said.“All we would need are lenses to focus the light and a fiber to guide it. Glassworks for  65  .It''''s already made in bulk, and itdoesn''''t require as much processing. Transparent ceramics might be even better.”   51.   A. disc   B. fiber   C. instrument    D. battery   52.   A. applications    B. components   C. resources   D. differences   53.   A. concerned    B. ignored   C. expected   D. noticed   54.    A. conduct   B. produce   C.use   D. consume   55.   A. reactive   B.preferable   C. due    D. equivalent   56.    A. light   B. electricity   C.chemical   D. gas   57.   A. plant    B. source   C. equipment   D. line   58.   A. up   B. down    C. apart   D. together   59.   A. this   B. those    C. that   D.these   60.    A. material   B. device   C.detector   D. meter   61.   A. bright   B. faint   C. visible    D. intense   62.   A. more    B. as   C. much   D. such   63.   A. skill    B. technology   C. miracle   D. prototype   64.    A. extensive   B. interactive   C. selective   D.intensive   65.   A. all   B. some   C. others    D. both 查看更多 7个回答 . 2人已关注
施工与生产同时的安全措施? 应该检测好可燃气体的泄露,注意受限空间内的气体检测。 对于有腐蚀性的物质,要注意做好隔离防护,包括劳保着装、 耐酸碱 的 安全鞋 、护目镜等。 工作前要进行JSA分析,做好安全技术交底,及施工全过程的安全旁站监督。查看更多 8个回答 . 3人已关注
关于消防泵,在设计上的一些特殊要求? 首先,我自己也不是做设计的,在这里谈消防系统的一些技术要求,有些板门弄斧,因此错误的地方,也请各位盖德指教。卖弄是其次,交流和提高才是最重要的。 1、消防泵,除了稳压泵之外,其它的主泵,必须是 填料密封 ,而不能采用 机械密封 。原因是,机械密封会突然全部失效,而填料密封,失效形式是逐渐出现的。这点,可以参考NFPA20的相关条款。 2、柴油消防泵,其柴油机,必须是压燃式,而不能是电控式,虽然电控式(通过分层燃烧和提前燃烧等技术)的可以满足较高的排放指标,提高燃机效率。这同样是因为压燃式内燃机在性能上更加可靠。这个要求和说法,可以参考NFPA20; 3、根据NPFA20的规定,内燃机的铭牌功率,即ISO工况下的输出功率,在经过高程和最大环境温度折算之后,应满足泵在任何工况下的输入轴功率; 根据GB6245的规定,电机驱动泵的铭牌功率,应不小于水泵在150%额定流量下的输入功率的110%。事实上,也基本可以满足任何工况下的轴功率了。 4、用作消防的水泵,其泵轴一般应为青铜制作。这个没有见到规范要求的出处,但是我见过的国外设计院设计的消防泵,并跟国内浙江科尔的专家核实过,确实国外都要求采用青铜的轴,理由是,青铜跟铁之间不会发生抱死。而如果采用普通合金,存在这种额外的风险; 5、用作消防的水泵,一般都不要求用口环。这个要求的出处同样不是很清楚。但同样跟国外的厂家和国内的科尔交流过,都确认,国外确实都不要口环,理由同样是担心出现叶轮与泵壳之间发生锈蚀或抱死。这当然会导致泵的效率的降低,但会提高设备的可靠性; 6、用作消防的水泵,根据FNPA20,会要求在泵的进出口上安装压力表。国内的规范没有见到类似的要求; 7、用作消防的水泵,应具有泵壳自动排气装置; 8、消防泵的联轴器,尤其是主泵,我见到的国外生产的,一般都没有采用API 610或API 682的膜片式联轴器,大多都采用塑料梅花型的联轴器,或者是万向节联轴器。个人的理解,相比膜片式联轴器,这样的联轴器的可靠性应该会更高一些吧。至于其与膜片式联轴器之间的优缺点,没有比较过。我的理解,万向节的应该是比API 682的联轴器要皮实一些吧。 这些,是基于个人观察,并查找规范或联系相关厂家专家核实后的一些跟普通 离心泵 相比要求不一致的地方。 此外,需要注意的是,国际项目的消防泵,一般都会要求满足FM和U/L认证,包括泄压阀、压力表和止回阀等。但根据个人的使用经验,质量真的很烂。没有看过这两个规范,不清楚其内容要求。如果有明白人,也可以在这里讨论一下。 最后,想说的是,国内某些设计院,要求消防泵满足API 610标准,我认为这是非常不负责任的。从使用的角度看,二类泵完全可以达到消防泵的所有要求。而API 610的规定,比一类泵的要求还要苛刻得多,对应的价格,也会高出好几倍。更何况,从上面的8点要求看,局部的要求,消防泵比API 610要更严格一些。 写这些东西,是因为听说我们公司某项目的初步设计是国内一个听起来很牛的据说是国内第一家从事国际EPC的设计院做的,弄了一份儿,想学习学习的,结果非常失望。此前其实也看过国内其它设计公司做的设计,也都差不多吧--自己写的SPEC,自己都解释不清楚来龙去脉。查看更多 25个回答 . 2人已关注
急~请求大神帮忙指导aspen模拟过滤过程? 如题,设置参数神马的都不会,只会一点简单的精馏,从没做过过滤过程,还请各路大神指导查看更多 1个回答 . 3人已关注
求提高卤水掺加比例的措施。? 求提高卤水掺加比例的措施。 # + + 。 查看更多 0个回答 . 4人已关注
老师们,焦化汽柴油加氢装置原料直供料那家正式投用啊? 我公司焦化汽 柴油 加氢装置因焦化 混合油 中夹带焦粉多,造成加氢反冲洗频繁,直供料一直没有投用。请问 焦化汽柴油加氢装置原料直供料那家正式投用啊? 查看更多 0个回答 . 4人已关注
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请问臭气治理一般采取什么方式? 最近在写但设计单位没给具体的东西,谢谢!查看更多 6个回答 . 3人已关注
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压力变送器和温度变送器? 流程图没有标注的话,看是否有TE之类的,查看更多 14个回答 . 5人已关注
螺旋折流板式换热器工艺设计中的问题? 毕业论文是有关螺旋折流板的工艺设计,而螺旋折流板的壳侧传热系数和壳侧压力降的计算和普通弓形折流板的不一样,找不到公式。我在西安交大的英文论文里找到了几个公式,里面有涉及到斯特赫利克图表,我不知道这个图表出自哪里。 请问前辈们,有做过螺旋折流板工艺设计的吗?关于螺旋折流板和弓形折流板计算时具体哪些地方不一样,螺旋折流板怎么计算壳侧传热系数和壳侧压力降啊? 谢谢!查看更多 3个回答 . 2人已关注
注化专业中化学动力学章节,怎么学? 最近开始复习注化专业考试,我觉得自己最薄弱的地方在化学动力学上,天大和协会的书讲的侧重点部太一样,而且两本书都讲的比较浅,今天开始做协会的习题集,几乎没有完全自己解出来的题,都必须看后面的答案,还看的一知半解,似是而非,觉得人家结题的思路很有道理,但是回过头来,自己再做,还是不会。 想请教大家都是怎么复习这一章节的呢?如何应对考试的?尤其是2014年通过的大神们~~~谢谢谢谢!查看更多 1个回答 . 4人已关注
简介
职业:上海纳诺微新材料科技有限公司 - 工艺专业主任
学校:河南师范大学 - 化学化工学院
地区:四川省
个人简介:莪对妳旳爱就像埃菲尔铁塔旳构造、坚不可摧。查看更多
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