正常盘旋飞机油箱液面晃动与结构动力学分析

针对飞机油箱晃动流固耦合问题,采用ABAQUS与Star-CCM+联合仿真流固耦合方法,通过对比验证单向和双向流固耦合,确定了采用单向流固耦合方法分析油箱晃动流固耦合问题的可行性,并对某型飞机正常盘旋过程中的油箱晃动流固耦合问题进行研究。验证了满油状态下飞机油箱的结构安全性,并探究了不同充液率对飞机油箱晃动流固耦合效应的影响。结果表明:满油状态下飞机油箱结构安全性满足要求;充液率不同,各因素对油箱部件应力的影响程度不同。     

Influence of baffle position on liquid sloshing during braking and turning of a tank truck

The influence of baffle position on liquid sloshing during the braking and turning of a tank truck was studied using a volume of fluid (VOF) model. The forces,their positions and weight distribution during braking and the forces and rolling moment during turning were calculated. The reliability of the calculation method was validated by comparisons with experimental results. The results showed that during braking,liquid splashes in the tank and the maximum forces and G (the ratio of weight acting on the front axle to the rear axle) are large when A (the ratio of the arch area above the baffle to the area of cross section)≤0.1. When A≥0.2,as the position of the baffle is lowered,the maximum of Fx (the force in direction x) first decreases then increases,and the maximum of Fy (the force in direction y) and G increase. During turning,liquid splashes in the tank and the maximum forces and M (the rolling moment) are large when D (the ratio of the arch area above the baffle to the area of cross section)≤0.2. When D≥0.3,as the position of the baffle is lowered,the maximums of Fy,Fz (the force in direction z) and M increase.     

《梅雨之夕》的U型和倒置U型的原型叙事结构

被称为"现代心理小说探索者"的施蛰存,是20世纪30年代中国"新感觉派"的重要代表人物,其代表作<梅雨之夕>采用意识流的表现形式,以诗歌化的叙事笔法,探索现代都市人隐秘微妙的内心世界,具有较高的文学价值和深刻的社会现实意义.     

基于BP神经网络PID算法的水箱液位控制系统设计

针对水箱液位这样一个多干扰、大惯性、高度非线性系统控制性能优化较困难,传统的控制策略在控制精度、灵敏度以及系统稳定性均存在缺陷,充分利用神经网络具有非线性函数逼近能力,构造神经网络PID自整定控制器,在解决高度非线性和严重不确定系统方面具有较好控制能力.解决了传统PID控制算法难以保证系统在任何工况条件下始终具有最佳控制性能的难题.仿真结果表明,该控制能使系统达到较好的控制效果.     

老板椅U形板折断的钳工修复技术

钳工作为机械行业的传统工种,工艺技术日趋成熟,在企业生产和工业中具有不可替代的应用价值.钳工操作设备相对简单,以手工工具为主,在一些小型零部件的修复中具有较好的作用.本文通过一张老板椅U形板折断后的钳工技术修复,得出钳工技能在生活中的具体应用,达到学有所用,实现知识转化.     

油罐注油蒸发损耗的实验测定

利用油品蒸发损耗及油气回收测试平台,实测了油罐不同装油速度、装油口高度和罐内气体空间初始油气浓度对油气浓度、损耗率以及气液比的变化规律.结果表明,低装油口装油时,液面上升速度为0.371～0.557 mm/s,对油气浓度影响不大;当液面上升速度为0.371～1.114 mm/s时,高装油口装油时损耗率为2.45‰～4.00‰,而低装油口装油时损耗率为1.08‰～2.09‰;当液面上升速度为0.557～1.114 mm/s时,低装油口装油时的气液比为1.13～1.30.研究结果对现实生产管理有重要的指导意义,可为降低油品蒸发损耗、减少环境污染提供依据.     

浅谈U型量水堰技术在冯家山灌区的应用

根据冯家山灌区工程现状和渠道量水设施存在问题,通过介绍U型抛物线形量水槽的结构与优点、相关数据确定、适用条件以及制做方法,总结其在冯家山灌区应用和推广,为灌区完善量水计水设施提供参考和借鉴。     

外电场作用下柔性模型水的分子动力学模拟

1 Introduction Water is the most common liquid in nature and it isalso i mportant in numerous chemical and biologicalprogresses . With the availability of computers , MonteCarlo (MC) and molecular dynamics (MD) si mulationshave beenintroduced and efforts have been devoted toexamining the microscopic structure and dynamicproperties of liquid water utilizing computer si mula-tions[1-8].It is known that liquid water is totally con-nected by random tetrahedral hydrogen-bonds net- work[1 ,2]. Ho…     

幼儿园自主游戏中的U型指导路径探析

通过对幼儿园自主游戏实践进行审视与反思,发现教师在观察、介入与指导实施中仍存有一些问题,而U型理论提出了一种向正在生成的未来学习的理论范式,将其观点和自主游戏相联系,能够为自主游戏的教师指导提供一种理论观照。以U型理论为依据探索自主游戏的U型指导路径,在融入情境充分观察、深入源头理解幼儿的游戏、创建原型实施指导的过程中确保指导的有效实现,以使幼儿在自主游戏中更好地获得发展。     

《少年维特的烦恼》中的 U形叙事结构

基督教文化是西方传统中不可分割的组成部分,对西方文学产生了巨大的影响。在《少年维特的烦恼》这部看似反叛基督教的小说中,实则隐含了诺思洛普·弗莱在研究《圣经》时所总结出的U形叙事结构。主人公维特疏离上帝,从 U形顶端落入痛苦的谷底,之后在信仰的指引下回升到开始时的高度,重新得到了上帝的垂爱,归于心灵的宁静与幸福。维特的遭遇十分清晰地向我们构建了“人神疏离———经历苦难———因信向死”的U形结构,从而闪现出小说中被隐匿的神学思想。     

论《魔戒》中的《圣经》U型叙事模式

托尔全的奇幻巨薯《魔戒》巧妙而显明地运用了源自《圣经》的U型叙事模式。小说的情节铺陈（主要人物的命运起伏和与之相关的地域兴衰）充分地彰显了U型模式。而圣经叙事模式则在深层次上映衬并传达了《魔戒》中富含基督教意蕴的主题寓意：善恶冲突观、信念以及希望的价值。这也给长久以来关于《魔戒》的宗教属性争论提供了新思路和新思考。     

Experimental study and numerical simulation of the sludge concentration in a sedimentation tank

Sedimentation tanks and clarifiers play a significant role in an active sludge system, and the efficiency of the whole system is closely related with the design and operation of the sedimentation tanks. This paper focuses on the sludge concentration in each cross-section of the sedimentation tank. We measured the sludge concentration to explore its distribution inside the tank, carried in-situ tests to research the fluid pattern and real operational rules of the sedimentation tank. We also used the computational fluid dynamics (CFD) software, PHOENICS 3.5, to simulate the solid-liquid two-phase fluid inside the tank and describe the sludge concentration distribution. The numerical results indicate obviously a sludge-water interface and a compression interface inside the sedimentation tank, a stratified sedimentary region with uniform concentration and a compression region with high concentration at the bottom of the tank. Although the simulated concentrations deviated slightly from those of in-situ tests, they were still acceptable for identifying the sludge interfaces and fluid pattern inside a sedimentation tank, which are important parameters for optimizing the tank size and improving the settling efficiency.     

基于单片机的坦克炮仰角控制实验装置设计

为了模拟坦克炮在行进中的炮身摆动控制,设计了坦克炮仰角控制实验系统.实验系统由物理实验对象和基于单片机的数字控制器构成,可以使得路面起伏所造成的炮身摆动得到有效控制.实验表明,该实验装置在跟踪低频正弦信号和低频随机信号时,达到了坦克炮控系统的精度要求.     

Visualization of Wormlike Micelle Fluid Flow in a Mixing Tank

In this study,particle image velocimetry was applied to investigate flow fields of wormlike micelle(WLM) fluids in a mixing tank equipped with a four-blade,down-pumping,pitched blade turbine. First,the rheology of WLM fluids was investigated,and the Carreau model was utilized to describe their apparent viscosity. Then,the effects of the rotation speeds and rheological properties on the flow fields were studied using different WLM fluids at different rotation speeds. The results revealed that with increasing Reynolds number,the discharge angle decreases and the carven size increases. Furthermore,elastic effects of WLM fluids lead to a more curved flow and a smaller carven.     

Absorption of NO2 into Na2S solution in a stirred tank reactor

To understand the absorption mechanism of nitrogen dioxide into a sodium sulfide solution, a stirred tank reactor with a plane gas-liquid interface was used to measure the chemical absorption rate of diluted nitrogen dioxide into sodium sulfide solution. The absorption rates under various experimental conditions were measured and the effects of experimental conditions on nitrogen dioxide absorption rate were discussed. The results show that, in the range of this study, nitrogen dioxide absorption rate increases with increasing sodium sulfide concentration, nitrogen dioxide inlet concentration, and flue gas flow rate, but decreases with increasing reaction temperature and oxygen content in flue gas.     

Molecular dynamics simulation study on behaviors of liquid 1,2-dichloroethane under external electric fields

Molecular dynamics simulation was carried out to study the behavior of liquid 1,2-dichloroethane molecules under external electric fields including direct current field, alternating current field and positive-half-period cosin field. The maximum applied field strength was 10⁸ V/m, the maximum frequency of the alternating current field and that of the positive-half-period cosine field was 10¹² Hz. The simulation revealed that the field type and field strength act on the population of the molecular configuration. In the strong direct current field, all trans forms converted completely into gauche forms. Order parameter and the correlation of the system torsion angle were also investigated. The results suggested that these two dynamical parameters depended also on the field type and the field strength. The maximum of order parameter was found to be at 0.6 in the strong direct current field.     

Molecular dynamics simulation study on behaviors of liquid 1,2-dichloroethane under external electric fields

ＩＮＴＲＯＤＵＣＴＩＯＮＭｏｌｅｃｕｌａｒｄｙｎａｍｉｃｓ (ＭＤ)ｓｉｍｕｌａｔｉｏｎｗａｓｆｏｕｎｄｔｏｂｅａｎｉｍｐｏｒｔａｎｔｍｅｔｈｏｄｏｌｏｇｙｆｏｒｓｔｕｄｙｏｆｃｏｎｄｅｎｓｅｄｍａｔｔｅｒ (Ｔｓｕｚｕｋｉｅｔａｌ.,1 996) .Ｋｉｓｅｌｅｖａｎ     

Absorption of NO2 into Na2S solution in a stirred tank reactor

To understand the absorption mechanism of nitrogen dioxide into a sodium sulfide solution, a stirred tank reactor with a plane gas-liquid interface was used to measure the chemical absorption rate of diluted nitrogen dioxide into sodium sulfide solution. The absorption rates under various experimental conditions were measured and the effects of experimental conditions on nitrogen dioxide absorption rate were discussed. The results show that, in the range of this study, nitrogen dioxide absorption rate increases with increasing sodium sulfide concentration, nitrogen dioxide inlet concentration, and flue gas flow rate, but decreases with increasing reaction temperature and oxygen content in flue gas.