流体流动时出口阻力的两种考虑方法

工业上流体输送是普遍存在的,而在输送过程中流体流动阻力的计算是非常重要的,本文介绍两种出口阻力的考虑方法,其计算结果是相同的。     

金属铝置换硝酸中氢的实验设计

成功地设计了金属铝置换硝酸中氢的实验装置与方法，旨在探索金属铝与硝酸的化学性质以及深刘理解硝酸浓度影响其产物的规律．研究发现，室温下用去膜并经氯化汞溶液处理过的铝箔与一定浓度的稀硝酸作用可产生氢气，而未经氯化汞溶液处理的铝箔与稀硝酸作用几乎检测不到氢气的生成．进一步研究显示硝酸的最高浓度为1．6mol／L，产生氢气最快时硝酸浓度为0．07mol／L．     

超临界二氧化碳在日用化工中的应用

介绍了超临界流体的特性、萃取原理，超临界二氧化碳作为SFE溶剂萃取精油、油脂和色素及作为化学反应介质在日用化工中的应用。     

静态各向异性荷电流体内部引力场

本文得到了质量密度和电荷密度都随半径变化的静态球对称各向异性荷电流体的E—M方程的一组严格解,当参数取一些特定值时,本解可退化为多个已知的严格解。     

液固两相槽道流中柱状粒子取向的数值研究

对柱状粒子在槽道流场内的运动进行数值模拟，然后用统计方法得出大量柱状粒子的取向分布；给出了粒子长径比、粒子密度和流场区域对粒子取向分布的影响．计算结果表明，柱状粒子长径比的变化对粒子取向分布的影响不明显，粒子密度对粒子取向分布有一定影响，而流场区域所造成的流场横向速度梯度对粒子取向分布有重要影响．随着流场横向速度梯度增大，粒子取向趋势愈加明显，且当流场横向速度梯度增大到一定程度时，粒子取向都趋向于流动方向．文中部分结果与相关实验进行了比较，两者定性吻合较好。     

Rational scale of urban rail transit network based on system dynamics

Optimization design and experimental research for space intelligent structurecapacity, high efficiency and low pollution. Estimating URT network scale is the key to ensure the scientificity and feasibility of its construction. The existing studies on rational scale of URT network have not dealt with the interaction of supply and demand. This paper describes the establishment of a system dynamics model of rational URT network scale determination, considering the interaction between URT construction and city social economic development as well as the dynamic equilibrium of capital supply and traffic demand, and the verification of the model validity by applying it to the case of Wuhan City’s URT construction.     

计算流体力学软件在汽车气动问题研究中的应用

汽车在行驶过程中受到空气的作用力,会对汽车运动产生影响。汽车气动特性的研究是汽车设计研发的重要内容,随着计算机技术与数值计算方法的发展,计算流体力学（CFD）在汽车气动特性的研究中得到日益广泛的应用,特别是各类计算流体力学商业软件使其参与工程设计成为可能。文章在介绍计算流体力学的基础上,结合实例对计算流体力学软件在汽车气动问题研究中的应用进行了探究。     

绪论课的地位作用与讲授策略

论述了绪论课的地位、作用与讲授策略,指出绪论课的教学目的。强调绪论课就是要回答为什么学、学什么、怎么学三个基本问题,概述了机电系统动力学绪论课的教学实践成果。     

杏仁油提取的各种工艺方法与研究

杏仁油是一种应用广泛的植物基础油,基础油和精油一起应用于芳香疗法中。大多数的植物精油具有强烈的刺激性,无法直接被人体吸收,只有在基础油中稀释后才能使用。基础油是在低温条件下制取的,温度不高于60℃,这就使得油脂中的矿物质、维生素以及脂肪酸等保存良好,具有优越的滋润滋养特质。本文利用杏仁提取杏仁油,主要综述了水代法、水酶法、冷压榨法、浸出法、超临界萃取法、超声波提取法等主要提取方法。     

Dynamics and manipulation of ferroelectric domain walls in bismuth ferrite thin films

Ferroelectric domain walls differ from domains not only in their crystalline and discrete symmetry, but also in their electronic, magnetic, and mechanical properties. Although domain walls provide a degree of freedom to regulate the physical properties at the nanoscale, the relatively lower controllability prevents their practical applications in nano-devices. In this work, with the advantages of 3D domain configuration detection based on piezoresponse force microscopy, we find that the mobility of three types of domain walls (tail-to-tail, head-to-tail, head-to-head) in (001) BiFeO₃ films varies with the applied electrical field. Under low voltages, head-to-tail domain walls are more mobile than other domain walls, while, under high voltages, tail-to-tail domain walls become rather active and possess relatively long average lengths. This is due to the high nucleation energy and relatively low growth energy for charged domain walls. Finally, we demonstrate the manipulation of domain walls through successive electric writings, resulting in well-aligned conduction paths as designed, paving the way for their application in advanced spintronic, memory and communication nano-devices.