Application of interval Multi-attribute Decision-Making Method to Aeroengine Performance Ranking

Introduction The performance deterioration of aeroengine isone of the key factors which may induce aircraft cata-strophic events. With the expansion of airline fleets,the number of aeroengines increase dramatically.Because performance parameters can refle…     

Hybrid process of fabricating high-quality micro wine-glass fused silica resonators

A new hybrid method, which combines improved glass-blown technology with wet etching, is reported to fabricate micro wine-glass resonators with high-quality fused silica. The optimum placement is compared to achieve the resonators with good shell shape. The typical shell diameter is about 4mm and its thickness covers from dozens to hundreds of micrometers. The etching rates in corrosion solutions with different ratios and at different thicknesses of hemispherical shells are studied. We also conclude how to precisely control the thickness. The corrosion solutions with different ratios of HF solution to NH₄F solution make the spherical shells rougher in different degrees. The best roughness is 0.581 nm in the 1: 8 ratio corrosion solution while the original roughness is 0.537 nm. This fact shows that the resonator remains atomically smooth surface. Based on the glassblowing spherical fused silica structure, the thickness of the resonator is effectively controlled by buffered oxide etch (BOE) technology according to the measured etching rate. The measured resonant frequency of the hemispherical shell at ambient pressure and room temperature is 1.75 kHz of rocking mode which is close to the simulated frequency. Using such a low-cost hybrid approach, we can fabricate high-quality microscale resonators in batch.     

Calculation of strain amplification matrix for strain invariant failure theory based on representative volume element models with periodical boundary condition

Strain invariant failure theory (SIFT) is a micro-mechanics-based failure theory for multi-scale failure analysis of composite materials originally proposed by Gosse and Christensen. In this paper, the approach for obtaining strain amplification matrix which is a key step for the execution of SIFT is improved by adopting representative volume element (RVE) finite element models considering periodical boundary condition, based on which more actual deformation mode is reflected. The deformation modes and strain data at the characteristic points of the centroid cell of multi-cell RVE model are analyzed and taken as a reference. It can be concluded that more reasonable deformation mode and relationship between the micro-mechanical and macro-mechanical strain states are obtained by employing the new model. Finally, numerical examples are provided to illustrate the determination of strain amplification factors within the RVEs considering periodical boundary condition at the characteristic points.     

上海市历史城区震后应急救援路网评价与优化

随着我国城市化进程加快,自然灾害问题也日渐凸显,作为主要自然灾害之一的地震正在严重影响着我国城市的公共安全.城市交通系统是城市重要的生命线,因此研究震后城市应急救援道路网络连通可靠度具有重要的现实意义.历史城区由于其建筑多为老旧平房,抗震性能差,而且城区道路空间局促,在遭遇地震时路网更易堵塞.本文以上海豫园区域路网为例,基于瓦砾堆积模型对震后路段通行概率进行计算,采用蒙特卡洛模拟方法对路网节点连接可靠度进行计算,对震后路网路段单元和节点的可靠性进行评估,并在此基础上判别关键路段和优化应急医疗救援路径.     

竖向预应力作用效果的数值模拟与预应力损失的试验研究

对箱梁竖向预应力筋张拉引起的混凝土竖向应力和螺纹钢筋的应力进行了有限元计算和现场测试分析,测试结果表明预应力损失离散性很大,而且预应力损失可能高达50%.这是由于箱梁的高度有限,竖向预应力筋的长度都比较短,因而在达到张拉控制应力时高强精轧螺纹粗钢筋的伸长量有限.目前的竖向预应力锚固技术尚存在不足,在锚固时稍有不慎造成钢筋回缩量偏大,很容易造成预应力损失.     

浙江地区轨道交通发展刍议

浙江省是我国经济大省、交通小省。本论文在对完善浙江地区轨道交通建设提出设想的基础上，对轨道交通建设资金的筹措方法和规划浙江地区轨道交通线网时需注意的几个问题作以分析。     

黄果树隧道软弱地带初期支护下沉侵限的整治技术

黄果树隧道是上瑞高速公路镇宁~胜境关段的一座公路隧道,出口右洞YK18 067~ 092的煤系地段处于F 12断层破碎带内,围岩为炭质泥页岩,呈软流塑状,属Ⅰ类围岩。该段施工后,初期支护发生严重变形,钢支撑被压弯,下沉量严重侵入建筑限界。文中介绍了侵入建筑限界部位及继续向前掘进的施工技术。     

公路工程招标过程中报价评分方法的探讨

就我国公路工程招标过程中采用的报价评分模式进行了简要的介绍和比较,并针对目前出现的围标现象,对完善招标办法提出了自己的建议。     

基于分层壳元法多梁式T梁的极限承载力评估

基于分层壳元法,对钢筋混凝土多梁式T梁的极限承载力问题进行了研究。建立实体退化壳元模型后,推导了壳元位移场,用分层壳元模拟了多梁式T梁。基于Owen理论考虑了混凝土的材料非线性,并基于V.Karman假设考虑了结构的几何非线性。通过多梁式T梁实例分析,结果表明,应用分层壳元法能正确地进行多梁式T梁的非线性分析,能有效地评估结构的极限承载力,且支承形式对多梁式T梁的极限承载力有很大影响,研究表明应选择修正的铰支-弹性支承形式。     

苏拉马部大桥钻孔桩泥浆牲能研究

在水敏性岩土体中进行钻孔灌注桩施工时,泥浆的失水量指标是钻孔能否成功的重要因素。通过对泥浆性能及适用范围的对比,阐明高分子聚合物泥浆不适合循环钻作业,介绍了苏拉马都大桥钻孔桩施工时选用CMC膨润土泥浆的原因,并对使用海水配制膨润土泥浆可行性进行了分析。