Effects of inclined magnetic field on mixed convection in a nanofluid filled double lid-driven cavity with volumetric heat generation or absorption using finite element method

A computational analysis has been performed on mixed convection in a double sided lid-driven cavity in the presence of volumetric heat generation or absorption. Effects of inclined magnetic field are also studied. The governing parameters are solved via Galerkin weighted residual finite element method in space and the Crank–Nicolson in time. Governing parameters are nanoparticle volume fraction (0.0?≤???≤?0.04), Richardson number (0.01?≤?Ri?≤?10), internal heat generation or absorption parameter $(?10\le q\le 10),$ inclination angle of magnetic field (0°?≤?γ?≤?90°) and Hartmann number (0?≤?Ha?≤?100). It is observed that the highest heat transfer is obtained in case of the maximum value of heat absorption. As a further finding, heat transfer decreases with increasing of Hartmann number and increases with increasing of nanoparticle volume fraction.     

五角芯型保偏光子晶体光纤(Q-PM-PCF)的双折射

提出了一种内层空气孔环含有五个空气孔的新型高双折射光子晶体光纤结构；采用全矢量有限元法进行分析,研究了该光子晶体光纤两正交偏振模的有效折射率和双折射,分别给出了该五角芯型保偏光子晶体光纤双折射随输入光波长和大空气孔半径的变化曲线.分析结果表明:该五角芯型保偏光子晶体光纤的双折射很易达到i0-3量级甚至更高,比传统保偏光纤的双折射至少高出一个数量级,合理设计光纤结构参数,该保偏光纤的双折射在1550 nm处可以达到6.5×10-3以上,甚至更高,适合应用于偏振特性及稳定性要求都较高的实际光纤传感系统,例如光纤陀螺.     

An alternative alpha finite element method with discrete shear gap technique for analysis of laminated composite plates

This paper presents an alternative alpha finite element method using triangular meshes (AαFEM) for static, free vibration and buckling analyses of laminated composite plates. In the AαFEM, an assumed strain field is carefully constructed by combining compatible strains and additional strains with an adjustable parameter α which can produce an effectively softer stiffness formulation compared to the linear triangular element. The stiffness matrices are obtained based on the strain smoothing technique over the smoothing domains and the constant strains on triangular sub-domains associated with the nodes of the elements. The discrete shear gap (DSG) method is incorporated into the AαFEM to eliminate transverse shear locking and an improved triangular element termed as AαDSG3 is proposed. Several numerical examples are then given to demonstrate the effectiveness of the AαDSG3.     

光刻物镜波像差检测平台移相装置的研制

针对基于剪切干涉原理的光刻投影物镜波像差检测设备中相移测量的需求,设计了一种移相装置.该装置采用了桥式放大机构,获得了较大放大比和相对紧凑的结构.从原理上对桥式放大机构进行了分析和讨论,得到了输入位移与其放大比之间的函数关系,并得到了其关系曲线.经过非线性有限元分析,对该装置的变形、受力和模态特性进行了验证.验证结果满足检测平台移相要求.     

厦门岛西水东调对海岛地下水质的影响分析

海岛是一种独特的生态系统, 由于其特殊的水文地质条件, 水资源相对比较贫乏, 一般都依靠地下水维持岛上生产生活用水, 如果地下水质受到影响, 则会带来较大的风险。岛内地表淡水湖泊水体污染严重。为了解决岛内地表淡水湖泊水体污染问题, 决定调用海水对其进行稀释, 而这一方案则有可能造成引水工程沿线海水侵入地下水问题。本文采用有限元方法分析从厦门西侧的筼筜湖经松柏湖调水到钟宅湾对周围地下水质和湖库水体的影响, 以及在丰水年和枯水年湖库水体和海水水体之间的补给关系。分析表明: 工程在一年左右对周围地下水的影响将趋于稳定, 工程沿线150～800m 范围内地下水的盐度产生了明显变化。在枯水年, 由于地下水位下降, 海水有可能会补给湖库, 引起湖泊盐度升高, 对工程沿线特别是饮用水备用水源湖边水库造成潜在的威胁。     

A new stabilized finite volume method for the stationary Stokes equations

In this paper we develop and study a new stabilized finite volume method for the two-dimensional Stokes equations. This method is based on a local Gauss integration technique and the conforming elements of the lowest-equal order pair (i.e., the P ₁–P ₁ pair). After a relationship between this method and a stabilized finite element method is established, an error estimate of optimal order in the H ¹-norm for velocity and an estimate in the L ²-norm for pressure are obtained. An optimal error estimate in the L ²-norm for the velocity is derived under an additional assumption on the body force. This work is supported in part by the NSF of China 10701001 and by the US National Science Foundation grant DMS-0609995 and CMG Chair Funds in Reservoir Simulation.     

�۱�ѵ�һ������W/Cu �ݶȲ��ϵ��ȹ������Ż�

针对不同体积分布指数p的W/Cu连续功能梯度材料的偏滤器第一壁结构，采用有限元软件计算了8MW.m?2稳态运行热加载以及等离子体破裂条件下1GW.m?2热流冲击下的力学响应。相同稳态加载条件下，W/Cu连续功能梯度材料的最优分布指数与分层梯度材料存在较大差异，其最优等效应力比分层梯度材料要小26%，表现出更优异的性能。在热冲击响应过程中，连续梯度W/Cu材料塑性损伤随p值不同也存在较大变化，其最优p值与其稳态运行时热应力最优p值存在一定差异，从第一壁应用条件考虑，应综合选取，最佳p值在1.2附近。综合来看，连续梯度W/Cu材料具有更连续变化的热物理属性及力学性能，在聚变堆第一壁结构设计中具有更大的应用潜力。     

选区激光烧结瞬态温度场模拟与测试方法研究

采用有限元方法，考虑实际的边界条件和热物性参量的变化，对Al2O3覆膜陶瓷粉末的选区激光烧结过程瞬态三维温度场进行动态模拟.通过比色测温法对红外热成像系统的发射系数进行修正后，对选区激光烧结过程瞬态温度场进行测试.数值模拟和实测结果显示，两者吻合较好.     

飞秒激光冲击AZ31B镁合金过程的数值模拟

采用有限元分析法对飞秒激光冲击AZ31B镁合金进行数值模拟,研究了激光冲击处理对镁合金变形过程的影响,分析了单脉冲激光冲击下材料内部的位移、动能、应力和应变的分布情况,得到了材料的瞬态速度和应变率变化过程.仿真结果表明,单脉冲飞秒激光冲击镁合金产生的塑性变形,可在材料表面形成微米级凹坑,中心点处最大位移为34μm,最大变形速度390m/s;在冲击初期,材料表面的应力和应变主要分布在冲击区域中心节点和边缘附近,并且得到镁合金的最大应力和最大应变率分别为955 MPa和1.8×106 s-1.研究结果能够为深入分析飞秒激光与镁合金作用时材料变形参量的变化规律提供数值理论依据.     

龙井水库大坝的渗流和稳定分析

本文以龙井水库大坝为例,运用有限单元法对粘土心墙坝的渗流进行分析计算,同时运用瑞典圆弧滑动法和简化Bishop法对粘土心墙坝的坝体稳定进行分析计算,在此基础上对水库大坝进行了渗流安全评价和稳定性安全评价。