前进速度对细长体在水中横向振动的影响(英文)

In this paper, the effects of forward speed on the lateral vibration of a slender structure in an infinite fluid are considered. By equating the bending stress of the structure with the hydrodynamic force acting on it, the equation which governs the fluid-structure interaction of a slender structure both vibrating and moving in water is obtained. Numerical results show that the influence of forward speed on the vibration of a slender structure in water is significant. It behaves like damping, reducing both natural frequencies and responses significantly.     

Modeling and simulation of torpedo acoustic homing trajectory with multiple targets

1Introduction Homingtrajectoryisthemostimportantaspectwithin exteriortrajectoryofanacoustichomingtorpedo.Thus,homingtrajectoryshouldreceivemuchattention intorpedotrajectorysimulations.Inthisresearchpro ject,atorpedoacoustichomingtrajectorysimulation progr…     

并行管道风险因素与事故交互作用分析

随着能源需求的不断增加,国内管道建设处在一个新的高潮时期,受各种因素制约,近距离并行敷设管道越来越多,给管道的建设和运行安全带来了新的挑战。通过分析并行管道设计、建设和运行阶段所面临的风险因素以及现有研究状况,并着重对管道运行阶段事故交互影响的失效概率进行了讨论。最后提出,对于并行管道的安全问题,不仅要考虑失效后果的严重程度,也应考虑管道发生事故后产生交互影响的概率问题,有效降低管道失效概率是解决并行管道安全问题的主要途径。     

An updated fast continuous contact detection algorithm and its implementation in case study of ice-structure interaction by peridynamics

Peridynamics is a mesh-free particle method that has been proposed in the last two decades. Contact between bodies in Peridynamics is a challenging and critical phenomenon that not only affects the computational efficiency of the algorithm, but is also closely related to the accuracy of the calculations. Therefore, it is important to develop a contact detection algorithm that is efficient, accurate, easy to extend to coupled numerical methods, and conducive to parallel computation. This study proposes a fast and continuous contact detection algorithm (FCCDA) that consists of two main parts. The first involves establishing a regular box bounding the entire target of collision to avoid the unnecessary calculation of material points that are not in contact with it, where this critically reduces the number of time-consuming calculations. The second part is a graphics-based algorithm to identify specific particles that penetrate the target. Both the numerical strategies and the mathematical methodologies of the FCCDA are discussed here. It was embedded into a Peridynamics system and examined in the context of a benchmark case for verification. Ship–ice interaction and propeller–ice interaction are also demonstrated using the proposed algorithm as examples of its applications to engineering.     

Numerical solutions for a two-dimensional airfoil undergoing unsteady motion

Continuous vorticity panels are used to model general unsteady inviscid, incompressible, and two-dimensional flows. The geometry of the airfoil is approximated by series of short straight segments having endpoints that lie on the actual surface. A piecewise linear, continuous distribution of vorticity over the airfoil surface is used to generate disturbance flow. The no-penetration condition is imposed at the midpoint of each segment and at discrete times. The wake is simulated by a system of point vortices, which move at local fluid velocity. At each time step, a new wake panel with uniform vorticity distribution is attached to the trailing edge, and the condition of constant circulation around the airfoil and wake is imposed. A new expression for Kutta condition is developed to study (i) the effect of thickness on the lift build-up of an impulsively started airfoil, (ii) the effects of reduced frequency and heave amplitude on the thrust production of flapping airfoils, and (iii) the vortex-airfoil interaction. This work presents some hydrodynamic results for tidalstream turbine.     

单面坡沙堆模型自组织临界性实验研究

沙堆模型是自组织临界状态理论的范例,介绍一种倾斜平面下半无限松散边坡坍塌沙堆模型实验研究,实验结果表明：沙堆的自组织临界性与颗粒的非均匀性有关,从而首次用实难方法证明了自组织临界状态受系统组织原则影响的猜测。     

磁浮列车与轮轨高速列车对线桥动力作用的比较研究

以德国Transrapid高速磁浮列车和日本新干线高速列车为基础,通过建立高速磁浮、轮轨列车与线桥动态相互作用模型,计算了不同行车速度(100～500km／h)和不同桥跨(12～32m)情形下高速列车与桥梁结构的动力响应,并进行了细致的对比分析。结果表明：磁浮列车在高速特别是超高速运行条件下的乘坐舒适性明显优于轮轨高速列车;磁浮与轮轨高速列车作用于轨道的每延米荷载大体相当;高速磁浮列车对小跨度(22m以下)桥梁的动力作用小于轮轨高速列车,而对中等跨度尤其是大跨度桥梁,轮轨高速列车较高速磁浮列车具有明显的优越性。     

Zfhag的锌指结构和同结构域的基因重组、表达和功能研究

报道了成功地亚克隆Ｚｆｈａｇ的锌指结构和同结构域基因，并将其在细菌体内表达成麦芽糖结合蛋白的融合蛋白的方法和结果，使用这些表达蛋白进行了蛋白－ＤＮＡ相互作用的研究。结果表明：ＭＢＰ－ＺＤ１和ＭＢＰ－ＺＤ２蛋白能与糖蛋白激素的α亚基基因、鼠生长激素（γ－ＧＨ）基因和促甲状腺激素β亚基（ＴＳＨ－β）基因的甲状腺激素反应成分（ＴＲＥ）结合，而不能结合含有天然ＴＲＥ的ＭＨＣ和Ｆ２Ｈ基因，及含有合成ＴＲＥ的ＤＲ４和ＰＡＬ寡核苷酸。     

轮轨噪声的预测

通过建立轮轨噪声预测模型 ,研究轮轨相互作用关系及由轮轨表面不平顺而引起的噪声 ,推导车轮、钢轨辐射噪声声压级谱 ,利用有关文献中给定的实验数据 ,验证轮轨噪声预测模型 ,并对我国既有线轮轨噪声进行了预测。     

高速铁路受电弓与接触网关系评价综述

电气化高速铁路通过接触N／受电弓系统向电力机车传输电能,弓网系统性能的好坏是机车能否实现快速、安全、高效运行的关键。本文阐述了弓网相互作用研究中的几个核心问题：振动耦合、滑动接触及与环境的作用,并对当前弓网系统研究方法进行了总结,指出了各种方法的优缺点,在对世界各国高速铁路受电弓与接触网关系评价标准进行系统总结的基础上,尝试为我国高速铁路弓网关系评价工作提出了若干建议。