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圆曲线轨道平移梁施工技术
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作者 董家海 《铁道建筑技术》 1995年第4期32-33,共2页
1 工程概况 沈阳市绕城高速公路的苏北大桥全长1361.16m,42孔,我处承担其中第20~29孔的施工任务,要在双柱式混凝土墩上架设30m预应力混凝土T形简支梁(每孔12片)。因为是在大桥中部施工,墩柱较高,桥位附近地形复杂,施工场地狭窄,待架梁... 1 工程概况 沈阳市绕城高速公路的苏北大桥全长1361.16m,42孔,我处承担其中第20~29孔的施工任务,要在双柱式混凝土墩上架设30m预应力混凝土T形简支梁(每孔12片)。因为是在大桥中部施工,墩柱较高,桥位附近地形复杂,施工场地狭窄,待架梁无法从两桥头运进,所以我们先把在桥下一侧空地上预制的混凝土梁运至桥下,再沿桥下铺设的圆曲线轨道将梁平移至与架梁平行的方向,然后垂直提升到桥墩上,再拖拉至各孔桥位上。施工场地平面布置见图1。 展开更多
关键词 公路桥 圆曲线轨道 平移 工程施工
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Point return orbit design and characteristics analysis for manned lunar mission 被引量:13
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作者 SHEN HongXin ZHOU JianPing +1 位作者 PENG QiBo LI HaiYang 《Science China(Technological Sciences)》 SCIE EI CAS 2012年第9期2561-2569,共9页
Point return orbit(PRO) of manned lunar mission is constrained by both lunar parking orbit and reentry corridor associated with reentry position.Besides,the fuel consumption and flight time should be economy.The patch... Point return orbit(PRO) of manned lunar mission is constrained by both lunar parking orbit and reentry corridor associated with reentry position.Besides,the fuel consumption and flight time should be economy.The patched conic equations which are adaptive to PRO are derived first,the PRO is modeled with fuel and time constraints based on the design variables of orbit parameters with clear physical meaning.After that,by combining analytical method with numerical method,a serial orbit design strategy from initial value design to precision solution is proposed.Simulation example indicates that the method has excellent convergence performance and precision.According to a great deal of simulation results by the method,the PRO characteristics such as Moon centered orbit parameters,Earth centered orbit parameters,transfer velocity change,etc.are analyzed,which can supply references to the manned lunar mission orbit scheme. 展开更多
关键词 manned lunar mission point return orbit orbit design orbit characteristics optimization
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Hyperbolicity of elliptic Lagrangian orbits in the planar three body problem
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作者 OU YuWei 《Science China Mathematics》 SCIE 2014年第7期1539-1544,共6页
The linear stability of Lagrangian elliptic equilateral triangle homographic solutions in the classical planar three body problem depends on the mass parameter β = 27(m1m2 + m2m3 + m3m1)/(m1 + m2 + m3)2∈ [0,... The linear stability of Lagrangian elliptic equilateral triangle homographic solutions in the classical planar three body problem depends on the mass parameter β = 27(m1m2 + m2m3 + m3m1)/(m1 + m2 + m3)2∈ [0,9] and the eccentricity e ∈ [0,1).In this paper we use Maslov-type index to study the stability of these solutions and prove that the elliptic Lagrangian solutions is hyperbolic for β &gt; 8 with any eccentricity. 展开更多
关键词 planar three-body problem Lagrangian solution HYPERBOLICITY Maslov-type index
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