Disjointness of Some Types of Extensions of Topological Transformation Semigroups

We extend (with some generalizations) Bronshtein's theorems about the disjointness of F-, PE-, V-extensions of minimal topological transformation groups.     

Positive stabilization of a parabolic equation by controls localized on a curve

We consider the stabilization of the nonnegative solutions of linear parabolic equation by controls localized on a curve. The main results of the article give a necessary and sufficient condition for positive stabilizability in terms of the principal eigenvalue of a certain elliptic operator. In case of positive stabilizability, some feedback stabilizing controls are indicated.     

一类线性抛物型方程组的特征有限元方法

本文应用特征有限元方法处理一类一维有界区域上的抛物型方程组,由于是第一类边界条件,对对流项系数作出假设,则避免了处理区域外的情况,最后给出收敛性定理.从误差结果看出,应用特征有限元可以增加时间步长,而不降低精度,数值实验也证实了这一点.     

Stability analysis of linear parabolic systems and removement of singularities in substructure: Static feedback

We analyze stability property of a class of linear parabolic systems via static feedback. Stabilization via static feedback scheme is most difficult and challenging when both actuators and observation weights admit spillovers. This arises typically in the boundary observation-boundary feedback scheme. We propose a simple static feedback law containing a parameter γ, and enhance the stability property or achieve (slightly) stabilization. In some situations, the evolution of the substructure of finite dimension contains singularities regarding γ. We show that these singularities are removed as long as the dimension is not large.     

Betti Numbers of parabolic U(2,1)-Higgs bundles moduli spaces

Let X be a compact Riemann surface together with a finite set of marked points. We use Morse theoretic techniques to compute the Betti numbers of the parabolic U(2,1)-Higgs bundles moduli spaces over X. We give examples for one marked point showing that the Poincaré polynomials depend on the system of weights of the parabolic bundle.      

Comparison of resonant tunneling in AlGaAs/GaAs parabolic and diffusion modified quantum wells

Double barrier resonant tunneling diode using annealing induced diffusion modified quantum well is proposed as a viable alternative to that using parabolic quantum well which requires complex techniques to fabricate it. The transmission coefficients are calculated using the hybrid incremental airy function plane wave approach. The room temperature current-voltage characteristics have been calculated using transmission coefficients. The current-voltage characteristics are found to be similar in both diodes.     

核磁共振成像

介绍核磁共振成像的物理原理及临床应用．     

新型多用磁场实验(演示)仪

介绍了新型多用磁场实验(演示)仪的原理特点和功能，并进行了实际测量，结果和理论符合很好，它是一种较好的电磁学实验仪器，具有较高的推广价值。     

Analysis and numerics for a parabolic equation with impulsive forcing

The paper considers a one-dimensional particle-continuum model, with impulsive interaction between the fluid and a number of pointwise particles. A simplification results in a system of ODEs coupled with a parabolic PDE forced by a nonlinear term involving a sum of Dirac delta functions. The existence of a mild solution is proved using a combination of energy estimates and semigroup theory. However, the regularity of these solutions is shown to be limited to C^0,1 by the impulsive terms. The convergence of a Galerkin method is established simultaneously with a proof of continuous dependence, and thus uniqueness, of solutions for the underlying system. The peculiarities of the system imply this analysis must be performed in L_∞. The C^0,1 regularity of the solution determines a suboptimal rate of convergence for the Galerkin method. The theoretical results are verified by MATLAB computations.     

互感系数相等证明方法集

给出互感系数相等(M12=M21)的多种证明方法．