A DLM/FD/IB Method for Simulating Cell/Cell and Cell/Particle Interaction in Microchannels

A spring model is used to simulate the skeleton structure of the red blood cell （RBC） membrane and to study the red blood cell （RBC） rheology in Poiseuille flow with an immersed boundary method. The lateral migration properties of many cells in Poiseuille flow have been investigated. The authors also combine the above methodology with a distributed Lagrange multiplier/fictitious domain method to simulate the interaction of cells and neutrally buoyant particles in a microchannel for studying the margination of particles.     

A NEW TRUST-REGION ALGORITHM FOR NONLINEAR CONSTRAINED OPTIMIZATION

We propose a new trust region algorithm for nonlinear constrained optimization problems. In each iteration of our algorithm, the trial step is computed by minimizing a quadratic approximation to the augmented Lagrange function in the trust region. The augmented Lagrange function is also used as a merit function to decide whether the trial step should be accepted. Our method extends the traditional trust region approach by combining a filter technique into the rules for accepting trial steps so that a trial step could still be accepted even when it is rejected by the traditional rule based on merit function reduction. An estimate of the Lagrange multiplier is updated at each iteration, and the penalty parameter is updated to force sufficient reduction in the norm of the constraint violations. Active set technique is used to handle the inequality constraints. Numerical results for a set of constrained problems from the CUTEr collection are also reported.     

高功率激光驱动器光束自动准直目标定位算法

为满足高功率激光驱动器光束自动准直的高精度和实时性要求,提出了一种快速高精度的自动准直目标定位算法。首先利用变结构元广义数学形态学边缘检测算法在充分提取图像边缘细节信息的同时抑制图像噪声的影响,然后采用拉格朗日多项式插值算法对圆目标轮廓进行快速亚像素定位,最后利用最小二乘拟合以及几何形心拟合的方法实现图像中光斑目标中心的精确定位。该算法在神光Ⅱ升级装置的光路自动准直中得以验证,实验结果表明八路预放光路准直时间小于3 min,主放光路准直时间小于7 min,主放输出光束近场准直准确度优于0.2%,远场指向准确度优于0.2(RMS)。     

On the rigidity theorems for lagrangian translating solitons in pseudo-Euclidean space I

Let f be a smooth strictly convex solution of
defined on a domain Ω C R^n, where ai, bi and c are constants. Then the graph Mvf of △f is a spacelike translating soliton for mean curvature flow in pseudo-Euclidean space with the translating vector（al, a2, . ., an; bz, b2, , bn）. In this paper, we will use alCfine technique to show a Berustein Theorem： if the graph Mvf is complete, then f（x） must be a quadratic polynomial and Mvf is an ailine n-plane.     

High-Order Hamilton＇s Principle and the Hamilton＇s Principle of High-Order Lagrangian Function

In this paper, based on the theorem of the high-order velocity energy, integration and variation principle, the high-order Hamilton＇s principle of general holonomic systems is given. Then, three-order Lagrangian equations and four-order Lagrangian equations are obtained from the high-order Hamilton＇s principle. Finally, the Hamilton＇s principle of high-order Lagrangian function is given.     

关于拉格朗日乘数法的几何意义

利用梯度和方向导数的概念讨论函数在曲线或曲面上的变化率,从而给出拉格朗日乘数法的一个直观的几何解释.     

关于条件极值的注记

文中结合反例,分析学生在求条件极值时的常见错误,给出求条件极值的正确方法.     

二维拉格朗日坐标系下气粒混合双向耦合对激波流场影响的计算

喷射颗粒与气体混合是内爆压缩领域的热点和难点. 针对喷射混合中的气粒双向耦合问题, 开展了理论建模、离散算法以及颗粒反馈对激波流场的影响研究. 建立了拉格朗日计算框架下的数学模型; 给出了耦合源项的离散算法; 开展了平面及汇聚构型条件下, 气粒双向耦合的数值模拟研究; 发现了颗粒反馈导致气体激波提速现象以及气区流场物理量分布形态的改变, 初步获得了量化分析结果. 本文建立的数学模型、计算方法和获得的新的物理认识, 为深入理解喷射混合现象、解决相关工程应用问题提供了重要理论支撑.     

柔性结构气弹效应在流动控制中的应用及进展

柔性结构与空气动力耦合形成的系统呈现出丰富的非定常、非线性流动和结构动力学行为,对其气动弹性效应合理地控制和利用,能够大幅度提高飞机机翼、风力机叶片等结构的气动性能,并使其具有气动自适应能力.本文总结了近年来与气弹效应应用相关的研究进展及存在的问题,具体介绍了薄膜翼型的流动控制特性、柔性壁面减阻技术以及Sinha扰流装置的发展过程、主要成果以及未来发展趋势,着重对相关试验、流固耦合数值分析、Lagrangian拟序结构动力学等理论分析方法进行总结,展示了气弹效应在流动控制方面的巨大潜力和深远的学术意义,以便更多的研究人员开展该领域的研究工作.      

哈密顿动力学的优越性

偶然拜读了贵刊在2006年第5期中刊登的文章《哈密顿和哈密顿力学》后颇有感触,该文谈及了哈密顿动力学的优越性问题,为了能够让读者更为全面清楚地了解这一问题,本文将哈密顿动力学与拉格朗日动力学进行比较再进一步做一些补充和总结。