“助学·励志·强能”构建高校贫困生立体帮扶模式

高校贫困生是一个特殊的群体,贫困生的消极心态不仅直接影响学习效率和精神面貌,而且极易造成人格的不健全和偏执心理。关注和加强贫困大学生思想政治工作,激励贫困大学生成长成才,是我们教育工作者的首要任务和职责。文中以广东交通职业技术学院谢强(化名)同学的成长经历为主要案例,介绍了学院基于"助学、励志、强能"全方位帮扶贫困生的工作方式和经验。     

转体桥梁下球铰及滑道支架无后浇带封固技术研究

下球铰、滑道及支架为桥梁平转法转体结构中关键部件,下球铰与上球铰组成转动结构核心,为桥梁平转提供转动面。常规预留后浇带分次封固、转盘一次性浇筑,在球铰、滑道支架安装处预留后浇凹槽,再安装定位下球铰及滑道,最后浇筑后浇带内剩余混凝土,完成球铰、滑道及其支架的封固。常规封固工艺工序较多、工艺复杂,且后浇带内作业空间小,施工难度大,混凝土施工质量难以控制。本文以山西省大同市大张高铁智家堡御河特大桥施工为背景,通过热固耦合仿真分析,论证取消后浇带的可行性,并对现场施工工艺进行总结,对同类工程具有重要指导意义。     

A numerical study of the effects of the longitudinal baffle on nickel ore slurry sloshing in a prismatic cargo hold

The nickel ore slurry sloshing in a rolling partially loaded prismatic cargo hold with a longitudinal baffle is investigated. A numerical model based on the volume of fluid (VOF) method and the non-Newtonian Herschel-Bulkley and Bingham equations is proposed to study the dynamic behavior of nickel ore slurry sloshing. The numerical model is solved by using the finite volume approximations and the dynamic mesh technique is utilized to handle the cargo hold's motion. After taking grid and time step independence study, the numerical results are compared with experimental data. Comparisons show good agreement in the cases investigated. Further, the relationship between the moment amplitude induced on the hold boundary and the excitation frequency is checked numerically. The ratio of baffle height to the initial cargo depth has been changed in the range of 0.0 ≤ h_B/d ≤ 1.2. The variation of the sloshing-induced moment and the deformation of the free surface under different baffle heights have been obtained and discussed. To clearly understand the sloshing behavior of nickel ore slurry, the sloshing of liquid water has also been carried out. Meanwhile, the dynamic viscosity of the nickel ore slurry is monitored. The critical baffle height with regard to the sloshing-induced moment and the elevation difference of the free surface at two sides of the cargo hold has also been presented and discussed.     

What determines rail transit passenger volume? Implications for transit oriented development planning

Transit oriented development (TOD) has been an important topic for urban transportation planning research and practice. This paper is aimed at empirically examining the effect of rail transit station-based TOD on daily station passenger volume. Using integrated circuit (IC) card data on metro passenger volumes and cellular signaling data on the spatial distribution of human activities in Shanghai, the research identifies variations in ridership among rail transit stations. Then, regression analysis is performed using passenger volume in each station as the dependent variable. Explanatory variables include station area employment and population, residents’ commuting distances, metro network accessibility, status as interchange station, and coupling with commercial activity centers. The main findings are: (1) Passenger volume is positively associated with employment density and residents’ commuting distance around station; (2) stations with earlier opening dates and serving as transfer nodes tend to have positive association with passenger volumes; (3) metro stations better integrated with nearby commercial development tend to have larger passenger volumes. Several implications are drawn for TOD planning: (1) TOD planning should be integrated with rail transit network planning; (2) location of metro stations should be coupled with commercial development; (3) high employment densities should be especially encouraged as a key TOD feature; and (4) interchange stations should be more strategically positioned in the planning for rail transit network.     

汽车排气系统脉动强化传热机理研究

为探索高温尾气、受热零部件和外部环境及相应物理场间的耦合关系,建立汽车排气系统内外流固耦合传热模型,并对模型及数值方法进行验证。数值试验表明,内流速度与温度的脉动都会使对流传热系数增大,且随着速度和温度脉动振幅的增长,传热近似呈2次函数关系增长,温度的脉动对强化传热效果更好。同时,提出了一种稳态速度等效法来预测发动机尾气脉动的强化传热效果,该方法也可以应用于排气系统的热应力及其变形的计算上。     

不均匀积水条件对路面行车安全的影响

采用Fluent有限元仿真分析软件,建立轮胎-路面-流体三维有限元模型,模拟不同水膜厚度和汽车行驶速度条件下汽车轮胎所受动水压力的理论变化值,定量地分析了水膜厚度和车速对积水路面车辆侧转角的影响以及积水段路面上车辆的横向稳定性能.研究结果表明:当水膜厚度大于胎面花纹深度时,动水压强随车速的增大而增加较快,且动水高压区由轮胎中间向轮胎边缘呈近似三角分布.在无驾驶员操控情况下,当汽车左右轮分别高速(＞ 90 km/h)行驶在干燥和积水路面,水膜厚度介于9～12 mm时,1 s后汽车的相对侧转角差超过最佳控制角度(25.),此时汽车操纵性开始下降;2 s后汽车的相对侧转角差已超过90.,车辆发生侧滑,易产生交通事故.     

大干溪I号隧道衬砌水压力分析

在岩溶富水地段,隧道衬砌实际上处在围岩应力场和渗透渗流场双场之中,渗流场的存在会导致围岩自稳能力降低,从而增加了围岩对衬砌的压力,同时渗流场的存在也会对隧道衬砌产生了渗透压力,研究了大干溪Ⅰ号隧道衬砌水压力,探讨了在渗流场和围岩应力场相互耦合作用下衬砌内力的变化情况,对富水段隧道衬砌的设计和施工有一定的借鉴意义。     

曹妃甸11-1油田地面地下一体化稳产挖潜技术研究

针对曹妃甸油田由于单点故障而导致的地面、地下生产能力受限问题,综合考虑地面设备处理能力—地下油藏潜力—井筒电泵生产能力之间的制约关系,以合理分配液量和电量、实现油田产量最大化为目的,开展了地面地下一体化稳产挖潜技术研究。通过系统优化,评价油田最佳产液量规模、单井合理产液水平及井筒电泵生产能力,建立"地下-井筒-地面"一体化流动模型,以实时优化油井工作制度,实现油田整体及单井的最优化生产。     

导流板对弯管流激噪声和流致振动的影响(英文)

The effect of a guide vane installed at the elbow on flow-induced noise and vibration is investigated in the range of Reynolds numbers from 1.70×105 to 6.81×105, and the position of guide vane is determined by publications. The turbulent flow in the piping elbow is simulated with large eddy simulation(LES). Following this, a hybrid method of combining LES and Lighthill's acoustic analogy theory is used to simulate the hydrodynamic noise and sound sources are solved as volume sources in code Actran. In addition, the flow-induced vibration of the piping elbow is investigated based on a fluid-structure interaction(FSI) code. The LES results indicate that the range of vortex zone in the elbow without the guide vane is larger than the case with the guide vane, and the guide vane is effective in reducing flow-induced noise and vibration in the 90° piping elbow at different Reynolds numbers.     

流体与结构砰击的全非线性模拟:综述（英文）

This paper presents a review of the work on fluid/structure impact based on inviscid and imcompressible liquid and irrotational flow. The focus is on the velocity potential theory together with boundary element method(BEM). Fully nonlinear boundary conditions are imposed on the unknown free surface and the wetted surface of the moving body. The review includes(1) vertical and oblique water entry of a body at constant or a prescribed varying speed, as well as free fall motion,(2) liquid droplets or column impact as well as wave impact on a body,(3) similarity solution of an expanding body. It covers two dimensional(2D), axisymmetric and three dimensional(3D) cases. Key techniques used in the numerical simulation are outlined, including mesh generation on the multivalued free surface, the stretched coordinate system for expanding domain, the auxiliary function method for decoupling the mutual dependence of the pressure and the body motion, and treatment for the jet or the thin liquid film developed during impact.