有结构壁面上液滴运动特征的耗散粒子动力学模拟

本文采用耗散粒子动力学方法, 研究了恒定外力驱动下液滴在有结构壁面上的运动过程. 通过研究液滴在通过壁面结构时前缘接触点和前进角的变化, 分析了液滴的运动特征. 研究结果表明, 在不同润湿性或不同外力驱动下, 存在使液滴运动最快的“最优”壁面结构, 并对其机理进行了讨论. 本文还探讨了壁面润湿性、热涨落以及外力对液滴运动状态的影响. 关键词： 微流体 有结构壁面 润湿性 耗散粒子动力学(DPD)     

热压/热变形纳米复合永磁体的制备和磁性能的研究

研究了热压热变形纳米复合永磁体制备的新工艺,探讨了制备高性能高各向异性块状纳米复合永磁体的新方法。以晶态纳米复合永磁粉末为原料,研究了热压热变形工艺参数与磁体密度和磁性能的关系。实验中制备出的热压热变形磁体的密度高达7.508g·cm-3,磁体的磁能积为61kJ·m-3。实验表明,温度是影响热压热变形磁体性能的重要因素。磁体在平行于压力方向的磁性能稍高于垂直于压力方向的磁性能,体现出微弱的各向异性。     

Numerical simulation of flow in Hartmann resonance tube and flow in ultrasonic gas atomizer

The gas flow in the Hartmann resonance tube is numerically investigated by the finite volume method based on the Roe solver.The oscillation of the flow is studied with the presence of a needle actuator set along the nozzle axis.Numerical results agree well with the theoretical and experimental results available.Numerical results indicate that the resonance mode of the resonance tube will switch by means of removing or adding the actuator.The gas flow in the ultrasonic gas atomization (USGA) nozzle is also studied by the same numerical methods.Oscillation caused by the Hartmann resonance tube structure,coupled with a secondary resonator,in the USGA nozzle is investigated.Effects of the variation of parameters on the oscillation are studied.The mechanism of the transition of subsonic flow to supersonic flow in the USGA nozzle is also discussed based on numerical results.     

Molecular dynamics of dewetting of ultra-thin water films on solid substrate

Molecular dynamics simulation is applied to study the instability and rupture process of ultra-thin water films on a solid substrate.Results show the small disturbance of the film will develop linearly due to the spinodal instability,whereas the interaction between solid and liquid has less influences on the initial growth.Then the rupture occurs and the rim recedes with a dynamic contact angle.The radius of the rim varies with time as the square root of t,which is consistent with the macroscopic theory available. Stronger interaction between solid and liquid will postpone rupture time,decline the dynamic contact angle and raise the density of water near the interface between solid and liquid.     

沿平板下落薄膜流动的研究综述

沿平板下落薄膜流动的时空演化一直是流体力学中一个相当活跃的研究领域.全面回顾了下落薄膜从长波近似方程到积分边界层方程, 从线性稳定性分析到弱非线性分析, 从首次失稳到二次失稳以及从有限振幅计算到直接数值模拟的发展历程, 总结了下落薄膜已有的理论结果和数值结果.此外,还介绍了沿加热平板下落的薄膜流动的最新研究进展, 概述了其它类型下落薄膜的研究情况.      

振动斜板上下落液体薄膜的数值模拟

用Galerkin有限元法数值模拟了振动斜板上的下落液体薄膜流动,研究了流场中不同强迫频率和初始扰动频率的影响.结果表明由于它们之间的相互作用,流场中出现低频信号,其在流场中的非线性效应使得表面波发生合并,加速了表面波的发展.对较高的强迫频率,这种效应更明显,且可观察到孤立包的产生.     

查儿酮类似物的合成及抗肿瘤活性研究

<正>查尔酮及其衍生物是芳香醛酮发生交叉羟醛缩合的产物,是合成多种天然化合物重要的有机合成中间体[1]。由于其分子结构具有较大的柔性,能与不同的受体结合,因此具有广泛的生物活性,包括:抗肿瘤、抑制和清除氧自由基、抗菌、抗病毒、抗溃疡和解痉等生物活性[2-7],抗过敏[8],除     

润湿性梯度驱动液滴运动的格子Boltzmann模拟

运用考虑了固体与液体间分子作用力的格子Boltzmann方法,数值研究了由于固液界面上表面张力梯度引起的Marangoni效应驱动的液滴运动.当表面张力梯度较小时,计算结果和前人的理论预测符合较好.而表面张力梯度较大时,由于液滴不变形和准平衡态等假设不再满足,理论预测的液滴运动速度高于数值模拟的结果.计算结果显示,在向亲水端运动过程中液滴内部出现旋涡结构,当润湿性梯度较大时,其前进速度和接触角随时间变化出现振荡.     

Guided motion of short carbon nanotube driven by non-uniform electric field

The molecular dynamics simulations are performed to show that in aque- ous environments, a short single-walled carbon nanotube （SWCNT） guided by a long SWCNT, either inside or outside the longer tube, is capable of moving along the nanotube axis unidirectionally in an electric field perpendicular to the carbon nanotube （CNT） axis with the linear gradient. The design suggests a new way of molecule transportation or mass delivery. To reveal the mechanism behind this phenomenon, the free energy profiles of the system are calculated by the method of the potential of mean force （PMF）.     

两级解耦卡尔曼滤波在平台惯导系统自主标定和对准中的应用

本文结合实际工程背景，采用两级卡尔曼滤波方法对平台惯导系统进行对准和标定，分别构造陀螺滤波器和加速度计滤波器，前者用于估计平台失调角和陀螺误差系数，后者用于估计加速度计误差系数，然后利用分离偏差滤波理论，将陀螺滤波器分解成状态滤波器和偏差滤波器，使滤波计算进一步得到简化。与一般卡尔曼滤波器相比，此滤波器的计算量以及计算机内存占用量都大为减小，而且估计精度很高