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气焊气割属于特危险工种。为避免工科大学生在气焊气割实训中出现普遍存在的的畏惧心理,进一步提高教学质量,采用虚拟与现实、联想与口诀等教学方法,帮助学生克服恐惧心理,并且乐于参与该教学实训实践。该教学方法也可以推广到其他工程实训教学。 相似文献
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与乙炔相比,无论工作性能还是气源条件,丙烷都具有相当的优势.介绍了一种新型氧气-丙烷气割嘴,以改进传统的采用氧气-乙炔的气割方式,并采用F luent软件对氧气-丙烷的混合情况进行了数值模拟,结果显示割嘴出口速度场分布均匀,氧气-丙烷的混合情况对燃烧有利,证明此种割嘴形式具有较好的混气效果. 相似文献
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在使用中碳钢厚板制造自动装料机的轨道过程中，板材发生多处开裂和断裂。采用金相和化学分析等方法对断裂件进行了分析。结果表明，厚板气割后产生较大的内应力和退火时加热不均匀而使局部出现粗大的魏氏组织是致断的主要原因。 相似文献
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许长庆 《河北工业大学成人教育学院学报》1999,(4)
0前言不锈钢以其优良的防腐性能和机械性能广泛应用于许多行业,它是一种银白色金属并带有金属光泽。在被用于装饰行业过程中,人们希望得到带有不同色彩的不锈钢装饰材料,这样就导致了彩色不锈钢的研究和开发。在1972年以前,人们研究了许多不锈钢的着色方法,但由于色膜疏松等原因,未能实现工业化生产。直到1972年国际镍公司发明了因科法（INCO）后,彩色不锈钢才进入了大规模工业化生产和商品化阶段,从装饰行业进入了航天航空、海洋工业、能源工业和化工等行业,许多国家开展了不锈钢的生产。美国德克萨斯洲的休斯敦市的一幢21层的… 相似文献
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杨清林 《兰州石化职业技术学院学报》2009,9(2):26-28
不锈钢复合钢板是一种由基层和复层组成的双层金属钢板,在石油化工装置中使用十分广泛。针对不锈钢复合钢板的焊接性特点,从坡口的选择、焊接方法、焊接材料、错变量的控制、焊后热处理和无损检测等工艺因素入手,阐述和提出了适合不锈钢复合钢板在石油化工设备制造生产中的焊接工艺措施。实践证明,这些工艺方法与措施在实际生产中可借鉴使用,并具有良好的针对性和实用效果。 相似文献
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聚苯胺作为一种新型的金属腐蚀防护材料,成为当前的一个研究热点.分别用原位聚合法和恒电位法在不锈钢表面合成导电聚苯胺,采用阳极极化曲线和电化学阻抗谱测试等方法研究它对不锈钢在3.5%NaCl溶液中的抗腐蚀能力,并用红外光谱和X射线衍射分析其结构.结果表明,覆有聚苯胺的不锈钢在3.5%NaCl溶液中的自腐蚀电位和极化电阻都明显增大,说明聚苯胺膜的存在明显减慢了不锈钢在氯化钠溶液中的腐蚀速度. 相似文献
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《山西教育(综合版)》2001,(4)
彩色不锈钢不锈钢是在冶炼时加入铬、镍等元素而制成的钢铁合金。随着科学技术的发展和人们物质生活水平的提高 ,科学家又在积极探索和研制彩色不锈钢 ,以使应用领域进一步得到扩展。彩色不锈钢是一种新型材料。它的制造过程并不是在不锈钢的表面简单地涂上一层着色剂 ,就能产生五彩缤纷的色彩 ,而要通过十分复杂的工艺过程来实现。目前所采用的方法是酸性浴氧化着色法 ,使不锈钢的表面生成一层透明的铬氧化物薄膜 ,光线照到上面之后 ,会因薄膜的厚度不同而产生不同的颜色。由于彩色不锈钢所具有的优异特性 ,其应用领域十分广泛。可用于高层… 相似文献
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在集输管网上加装防护套管时,由于护管切割变形导致组装、焊接困难,本文接合现场实际操作,制作护管紧固装置。应用后,有效地解决了变形,提高了焊接质量,缩短了施工时间。 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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罗艳萍 《读与写:教育教学刊》2008,5(6)
The communication of people partially is the communication of cultures. Culture has a direct effect on international commercial activities in all aspects. Different conceptions about time, space, equality, law and the like, lead people to deal with things in different ways. So to know cultures of the counterpart is to facil-itate our enterprises so as to have a smooth and successful communication in commercial activity. 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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Richard Denner 《海外英语》2007,(4):14-15
Rosco and I wait for the fishermen to return.I sit at a wooden bench near the store at Mt.Baker Resort and watch the clouds change shape. Rosco has my belt around his neck and an eight foot tow chain hooked to a tree. Dogs must be on a leash. Ducks and rabbits are loose. 相似文献