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1、专业好文档试卷代号：1 135中央广播电视大学2011-2012学年度第一学期“开放本科”期末考试液压气动技术 试题一、单选题（每题3分，共30分）1液压系统的工作压力取决于( )。 C负载2解决齿轮泵困油现象最常用方法是( )。 B开卸荷槽A4下列三位换向阀中位机能中，能实现系统卸荷的是( )。AH型5与节流阀相比较，调速阀的显著特点是( )。C流量稳定性好6在下列液压阀中，( )不能作为背压阀使用。 C减压阀7液压机床中往往采用快速回路，它的主要目的是( )，提高系统的工作效率。 B加快工作机构空载时的速度8有湿空气的压力为0. 106MPa，干空气分压为0.082MPa，若同温度下饱和水
2、蒸气分压为0. 062MPa，则此湿空气的相对湿度为( )。B38. 7%9等温过程的特征是( )。A气体的内能保持不变10气动系统使用( )是为了使各种气动元件得到润滑，其安装位置应尽可能靠近使用端，但绝不能安装在换向阀和气缸之间。D油雾器二、判断题（正确的打，错误的打，每题3分，共30分） 11液体的体积模量越大，表明该液体抗压缩的能力越强。( ) 12液压油对温度变化极为敏感，温度升高，粘度降低。( ) 13.相对压力有正、负之分，正的相对压力称为真空度；负的相对压力称为表压力。 ( ) 14.通常把既无粘性又不可压缩的液体称为理想液体。( ) 15双作用叶片泵既可作为定量泵使用，又可作
3、为变量泵使用。 16.先导式溢流阀的远程控制口可以使系统实现远程调压或使系统卸荷。( ) 17采用节流阀的进油路节流调速回路，其速度刚度与节流阀流通面积A及负载FL的大小有关，而与油泵出口压力无关。( ) 18将马赫数M a2。试读懂液压系统原理图，填写电磁铁动作顺序表。（电磁铁吸合标“+”，电磁铁断开标“一”）Winger Tuivasa-Sheck, who scored two tries in the Kiwis 20-18 semi-final win over England, has been passed fit after a lower-leg injury, while
4、Slater has been named at full-back but is still recovering from a knee injury aggravated against USA.Both sides boast 100% records heading into the encounter but Australia have not conceded a try since Josh Charnleys effort in their first pool match against England on the opening day.Aussie winger J
5、arryd Hayne is the competitions top try scorer with nine, closely followed by Tuivasa-Sheck with eight.But it is recently named Rugby League International Federation player of the year Sonny Bill Williams who has attracted the most interest in the tournament so far.The Kiwi - with a tournament high
6、17 offloads - has the chance of becoming the first player to win the World Cup in both rugby league and rugby union after triumphing with the All Blacks in 2011.Id give every award back in a heartbeat just to get across the line this weekend, said Williams.The (lack of) air up there Watch mCayman Is
7、lands-based Webb, the head of Fifas anti-racism taskforce, is in London for the Football Associations 150th anniversary celebrations and will attend Citys Premier League match at Chelsea on Sunday.I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport.For me it
8、s about how he felt and I would like to speak to him first to find out what his experience was.Uefa hasopened disciplinary proceedings against CSKAfor the racist behaviour of their fans duringCitys 2-1 win.Michel Platini, president of European footballs governing body, has also ordered an immediate
9、investigation into the referees actions.CSKA said they were surprised and disappointed by Toures complaint. In a statement the Russian side added: We found no racist insults from fans of CSKA. Baumgartner the disappointing news: Mission aborted.The supersonic descent could happen as early as Sunda.T
10、he weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) wh
11、ere our day-to-day weather lives. It will climb higher than the tip of Mount Everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e
12、can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform.They blew it in 2008 when they got caught cold in the final and they will not make the same mistake a
13、gainst the Kiwis in Manchester.Five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by Englands Josh Charnley in the opening game of the tournament.That could be classed as a weakness, a team under-cooked - but I have been impressed by the Kangaroos focus in their games since then.They have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, especially on their own goal-line, completing sets and a good kick-chase. Theyve b
