Stabilization for a Fourth Order Nonlinear Schrödinger Equation in Domains with Moving Boundaries

In the present paper we study the well-posedness using the Galerkin method and the stabilization considering multiplier techniques for a fourth-order nonlinear Schrödinger equation in domains with moving boundaries. We consider two situations for the stabilization: the conservative case and the dissipative case.     

计及弯曲刚度的印刷运动薄膜横向振动控制研究

研究了不同边界条件下,计及弯曲刚度的轴向运动薄膜横向振动的主动控制问题.建立计及弯曲刚度的印刷运动薄膜的计算模型.利用有限差分法,对轴向运动薄膜的振动微分方程进行离散,推导出轴向运动矩形薄膜横向振动控制系统的状态方程.采用次最优控制法,对不同边界条件下轴向运动矩形薄膜横向振动进行主动控制研究.计算结果表明：采用次最优控制法能够在短时间内迅速、有效地降低运动薄膜的振动强度,并使之衰减趋近于0.作动器作用在固定位置点处时,对运动薄膜施加控制后,四边简支边界条件下的控制效果好.作动器作用在不同位置点处时,两种边界条件下中心点处的控制效果最好.计算证明次最优控制法能够有效地抑制印刷过程中计及弯曲刚度的轴向运动薄膜的横向振动,从而提高印刷套印精度,保证精密印刷质量.     

Sine-Gordon方程的动态边界反馈镇定

考虑一端固定,控制输入在另一端的Sine-Gordon方程的动态边界反馈镇定问题.我们给出闭环系统的适定性,并利用乘子方法得到在动态边界反馈控制下闭环系统的多项式衰减率.     

On a decay rate for nonlinear extensible viscoelastic beams with history setting

In this paper we deal with a nonlinear extensible viscoelastic beam model whose memory term is considered in a history setting. The goal is to extend an approach on stability first provided by Guesmia and Messaoudi (J Math Anal Appl. 2014;416:212–228) to a class of viscoelastic beams/plates with nonlinear extensible and source terms. Our stability result contributes in clarifying how the constants appearing in the decay rate depend upon the nonlinearities and the size of initial data. Thus, it also complements some results dealing with this methodology.     

轴向运动粘弹性板的横向振动特性

研究了轴向运动粘弹性矩形薄板的动力特性和稳定性问题．从二维粘弹性微分型本构关系出发,建立了轴向运动粘弹性板的运动微分方程．采用微分求积法,对四边简支、一对边简支一对边固支两种边界条件下粘弹性板的无量纲复频率进行了数值计算．分析了薄板的长宽比、无量纲运动速度及材料的无量纲延滞时间对其横向振动及稳定性的影响．     

The residual velocity method applied to a steady free boundary-value problem of vector Laplacian type

We consider a free boundary-value problem based on a simplifiedmodel of two-phase flow in porous media. The model has two independentvariables on each side of the free interface. At the interfaceat steady state, five mixed Dirichlet and Neumann conditionsare given. The movement of the interface in time-dependent situationscan be reduced to a normal motion proportional to the residualin one of the steady-state interface conditions (the ellipticinterior problems and the other interface conditions are satisfiedat each time). Following previous work, we consider the useof other residuals for the normal velocity that have superiornumerical properties. The well-posedness criteria for this vectorexample are particularly clear. The advantages of the correctlychosen, non-physical residual velocities are demonstrated innumerical computations. Although the finite-difference implementationin this work is not applicable to general problems, it has superiorperformance to previous implementations.     

末端质量作用下变长度轴向运动梁的振动特性

对带集中质量,变长度(或速度)轴向运动梁的振动特性采用两种精确方法求解.首先,对变长度轴向运动Euler(欧拉)梁横向自由振动方程进行化简,通过复模态分析得到本征方程,并在有集中质量的边界条件下得到频率方程,用数值方法求解固有频率和模态函数.然后,采用有限元方法建立运动梁自由振动的方程,求解矩阵方程得到复特征值和复特征向量,结合形函数得到复模态位移.最后,将两种方法的计算结果进行了分析和对比.数值算例的结果表明：不同的轴向运动速度和集中质量对变长度轴向运动梁的振动特性有显著影响,两种计算方法的结果接近且均有效.     

带有未知内部扰动的星形Euler-Bernoulli梁网络的指数跟踪控制

该文研究了带有未知内部扰动的星形Euler-Bernoulli梁网络的指数跟踪控制问题.首先将该问题等价转化为跟踪网络与被跟踪网络的误差网络的镇定问题.利用滑模控制思想,对误差网络设计了非线性反馈控制方案.通过对状态空间选取适当的范数,运用单调算子理论得到了误差网络的适定性.通过构造适当的Lyapunov函数,证明误差网络按任一收敛率指数稳定.这表明跟踪网络能够按任一给定速率以指数速度跟踪到目标网络.     

Non-linear parametric vibration and stability analysis for two dynamic models of axially moving Timoshenko beams

Non-linear parametric vibration and stability of an axially moving Timoshenko beam are considered for two dynamic models; the first one, with considering only the transverse displacement and the second one, with considering both longitudinal and transverse displacements. The set of non-linear partial-differential equations of both models are derived using an energy approach. The method of multiple scales is applied directly to both models, and using the equation order one, the mode shape equations and natural frequencies are obtained. Then, for the equation order epsilon, the solvability conditions are considered for the resonance case and the stability boundaries are formulated analytically via Routh–Hurwitz criterion. Eventually, some numerical examples are provided to show the differences in the behavior of the above-mentioned non-linear models.     

赤道β-平面近似的无量纲线性浅水方程组的边值问题

应用分层理论所提供的方法,研究了赤道β-平面近似的无量纲线性浅水方程组的边值问题的适定性以及相应的识别方法.对于在超平面{x=f(y,t)}和{y=g(x,t)}的边值问题,分别给出了它们局部解的解空间构造.     

Stability and asymptotic behaviour of solutions of the heat equation

In this paper we study the boundary stabilization of the heatequation. The stabilization is achieved by applying either Dirichletor Neumann feedback boundary control. Furthermore, we considerthe asymptotic behaviour of the heat equation with general lineardelay or nonlinear power time delay. We prove that the energydoes not grow faster than a polynomial.     

Well-posedness and stability for an elliptic-parabolic free boundary problem modeling the growth of multi-layer tumors

In this paper we study a free boundary problem modeling the growth of multi-layer tumors. This free boundary problem contains one parabolic equation and one elliptic equation, defined on an unbounded domain in R2 of the form 0 〈 y 〈p（x,t）, where p（x,t） is an unknown function. Unlike previous works on this tumor model where unknown functions are assumed to be periodic and only elliptic equations are evolved in the model, in this paper we consider the case where unknown functions are not periodic functions and both elliptic and parabolic equations appear in the model. It turns out that this problem is more difficult to analyze rigorously. We first prove that this problem is locally well-posed in little H61der spaces. Next we investigate asymptotic behavior of the solution. By using the principle of linearized stability, we prove that if the surface tension coefficient y is larger than a threshold value y〉0, then the unique flat equilibrium is asymptotically stable provided that the constant c representing the ratio between the nutrient diffusion time and the tumor-cell doubling time is sufficiently small.     

Analysis of a Free Boundary Problem Modeling Multi- Layer Tumor Growth in Presence of Inhibitor

In this paper we study well-posedness and asymptotic behavior of solution of a free boundary problem modeling the growth of multi-layer tumors under the action of an external inhibitor. We first prove that this problem is locally well-posed in little Holder spaces. Next we investigate asymptotic behavior of the solution. By making delicate analysis of spectrum of the linearization of the stationary free boundary problem and using the linearized stability theorem, we prove that if the surface tension coefficient γ is larger than γ^＊ 〉 0 the fiat stationary solution is asymptotically stable provided that the constant c representing the ratio between the nutrient diffusion time and the tumor-cell doubling time is sufficient small.     

动态有限元法与水发汗冷却控制模型

本文研究了带活动边界的水发汗控制系统 ,用动态有限元的方法建立了水发汗控制模型     

Optimal boundary feedback stabilization of a string with moving boundary

Email: gugat{at}am.uni-erlangen.de Received on April 30, 2006; We consider a finite string that is fixed at one end and subjectto a feedback control at the other end which is allowed to move.We show that the behaviour is similar to the situation whereboth ends are fixed: As long as the movement is not too fast,the energy decays exponentially and for a certain parameterin the feedback law it vanishes in finite time. We considermovements of the boundary that are continuously differentiablewith a derivative whose absolute value is smaller than the wavespeed. We solve a problem of worst-case optimal feedback control,where the parameter in the feedback law is chosen such thatthe worst-case L^p-norm of the space derivative at the fixedend of the string is minimized (p [1, )). We consider the worstcase both with respect to the initial conditions and with respectto the boundary movement. It turns out that the parameter forwhich the energy vanishes in finite time is optimal in thissense for all p.