Proper orthogonal decomposition of oscillatory Marangoni flow in half-zone liquid bridges of low-Pr fluids

Proper orthogonal decomposition (POD) using method of snapshots was performed on three different types of oscillatory Marangoni flows in half-zone liquid bridges of low-Pr fluid (Pr = 0.01). For each oscillation type, a series of characteristic modes (eigenfunctions) have been extracted from the velocity and temperature disturbances, and the POD provided spatial structures of the eigenfunctions, their oscillation frequencies, amplitudes, and phase shifts between them. The present analyses revealed the common features of the characteristic modes for different oscillation modes: four major velocity eigenfunctions captured more than 99% of the velocity fluctuation energy form two pairs, one of which is the most energetic. Different from the velocity disturbance, one of the major temperature eigenfunctions makes the dominant contribution to the temperature fluctuation energy. On the other hand, within the most energetic velocity eigenfuction pair, the two eigenfunctions have similar spatial structures and were tightly coupled to oscillate with the same frequency, and it was determined that the spatial structures and phase shifts of the eigenfunctions produced the different oscillatory disturbances. The interaction of other major modes only enriches the secondary spatio-temporal structures of the oscillatory disturbances. Moreover, the present analyses imply that the oscillatory disturbance, which is hydrodynamic in nature, primarily originates from the interior of the liquid bridge. (C) 2007 Elsevier B.V. All rights reserved.

材料分叉的数值分析

通过与解析解法相对比,说明了分析材料分叉时采用数值法的特点.文中揭示了在单向和弱双向加载条件下材料分叉(平面剪切带和表面皱曲)的一些特征.单向拉伸的实验表明,所计算的临界值是合理的.

内凹式负压磁头气体动力特性

本文给出了一种用于磁盘机读/写功能的非接触起停式负压磁头滑块模型。通过求解修正Reynolds方程,计算出其稳态气动力特性。给出了磁头滑块与磁盘之间润滑气膜压强分布的立体图,滑块工作曲线及压力载荷随磁盘线速度、气膜厚度、减压槽深度的变化规律曲线。

关于太阳湍流发电机理论

本文介绍了太阳湍流发电机问题的双尺度平均场电动力学分析方法以及有关太阳发电机问题的研究结果:α,β效应及各种发电机模型。总结分析了现阶段太阳湍流发电机问题在观测和理论方面的主要困难。对其他的太阳发电机理论也进行了简要介绍。

全金属结构氩激光器的研究

本文简述全金属结构氩离子激光器实验的初步结果。该激光器以水冷分段铝片组成放电管,内径8毫米,有效放电长度300毫米。采用水冷铜环形冷弧阴极和水冷筒状阳极。

Convenção sobre os direitos das pessoas com deficiência : Decreto nº 6.949, de 25 de agosto de 2009, Decreto Legislativo nº 186, de 2008 e o texto da Convenção sobre os direitos das Pessoas com deficiência e de seu Protocolo Facultativo, assinados em Nova York, em 30 de março de 2007

Aprova o texto da Convenção sobre os Direitos das Pessoas com Deficiência e de seu Protocolo Facultativo, assinados em Nova York, em 30 de março de 2007.

Restrição para celebração de convênios e contratos de repasse com entes federados

Estudo sobre alternativas à fixação de limites mínimos para a celebração de convênios e contratos de repasse fixados no Decreto nº 6.170, de 25 de julho de 2007, com as modificações do Decreto nº 7.594, de 31 de outubro de 2011.

电磁流体管道流的进口段分析

最近有不少文章討論了导电流体在横向磁場作用下管內完全发展流动的規律,例如文献[1]。但是在确定这些結果的实用范围之前,必須估計出进口段的长度,即管道从进口处开始,直到中心流速和完全发展流动的中心流速相差1％处那一段的长度。文献[2]曾考虑过这一門題,并应用Rayleigh近似得出了一个适用于大Hartmann数情况的估計,文献[3]則考虑了小Hartmann数的流动。本文利用Langbaar假设来处理了同一問題,原則上对Hartmann数的大小没有限制;給出了一些数值結果,并和文献[2,3,7]的結果作了比較。

¿Chalés en el campo de tiro?

Duración (en horas): De 11 a 20 horas. Nivel educativo: Grado

橄榄石LiFePO_4第一性原理计算研究进展

锂离子电池是一种新型能源,与现有的可充电电池（铅酸电池、镉镍电池和金属氢化物镍电池）相比,在比能量上占有明显优势,目前比能量可高达170～180Wh/kg,是Cd-Ni电池的4倍，MH-Ni电池的2倍。锂离子电池的高T作电压（3．6V）使其相当于3节镉镍电池或金属氢化物镍电池的串连，有利于电池的小型化、轻量化。同时，又具有自放电率低（一般月自放电率小于6％）、长循环寿命的优点.，而且对环境友善，没有污染，是一种绿色能源。自从锂离子电池1991年成功进入世界市场，凭借以上优越性能，在手提电话，摄像机，笔记本电脑和各种便携设备方面的应用越来越广泛。随着新能源的不断开发和利用，对电解液和电极材料的要求也越来越高，特别是对环境的关注和对能源短缺的思考使得人们对锂离子电池进行了新的改进。开发新型电池正极材料是锂离子电池研究的一项重要内容，目前的研究处在实验阶段。由于候选材料的多样性，导致实验上消耗大量的人力、物力和财力，于是从理论上寻求一种计算方法对实验结果进行解释，对相关的材料进行稳定性和电化学性能预测，从而找出一些普遍性规律，已引起研究人员的广泛关注。Ceder于1998年在Nature杂志上发表了《使用第一性原理计算来指导锂离子电池正极材料合成》的研究论文，文中计算出LiAIO_2的嵌入电压高达5．4 V，但纯的LiAIO_2 是电子绝缘体，所以考虑用A1部分替代LiCoO_2 中的Co元素，可以调节电压值，还有利于提高质量比容量。从那时起，理论计算预测锂离子电池正极材料的性能越来越重要。