Zhangxin Chen

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In this paper we show that mixed finite element methods for a fairly general second-order elliptic problem with variable coefficients can be given a nonmixed formulation. (Lower-order terms are treated, so our results apply also to parabolic equations.) We define an approximation method by incorporating some projection operators within a standard Galerkin(More)
The purpose of this paper is to establish an equivalence between mixed and nonconforming nite element methods for second order elliptic problems on both triangular and rectangular nite elements in IR 2 and IR 3 , and to provide an analysis of multigrid methods for both methods based on the equivalence. We rst show that the linear system arising from the(More)
In the rst part of this paper, the mathematical analysis is presented in detail for the single-phase, miscible displacement of one uid by another in a porous medium. It is shown that initial boundary value problems with various boundary conditions for this miscible displacement possess a weak solution under physically reasonable hypotheses on the data. Then(More)
  • Zhangxin Chen, Bernardo Cockburny, Carl L. Gardnerz, Joseph W. Jeromex
  • 1995
Hysteresis in the current-voltage curve of a resonant tunneling diode is simulated and analyzed in the quantum hydrodynamic (QHD) model for semiconductor devices. The simulations are the rst to show hysteresis in the QHD equations, and con rm that bistability is an intrinsic property of the resonant tunneling diode. Hysteresis appears in many settings in(More)
This paper deals with development and analysis of a fully discrete nite element method for a nonlinear di erential system for describing an air water system in groundwater hydrol ogy The nonlinear system is written in a fractional ow formulation i e in terms of a saturation and a global pressure The saturation equation is approximated by a nite element(More)
Overexpression of Pokemon, which is an erythroid myeloid ontogenic factor protein, occurs in different cancers, including hepatocellular carcinoma (HCC). Pokemon is also reported to have an oncogenic activity in various human cancers. This study investigated the effect of Pokemon knockdown on the regulation of HCC growth. POK shRNA suppressed the expression(More)