SOLVABILITY FOR NONLINEAR ELLIPTIC EQUATION WITH BOUNDARY PERTURBATION

The solvability of nonlinear elliptic equation with boundary perturbation is consid- ered.The perturbed solution of original problem is obtained and the uniformly valid expansion of solution is proved.     

Transition mechanisms of translational motions of bubbles in an ultrasonic field

The translation behaviors of oscillating bubbles are closely related to the polymerizations and dispersions between them, which are crucial for the ultrasonic cavitation effect. In this study, six types of translational motion of bubbles with a wide range of sizes (2–100 μm) in the R₀₁-R₀₂ plane are investigated. Our results demonstrate that in addition (to the 2nd order harmonic), the 1/2 order subharmonic can change the bubble pairs from the three states of the attraction, stable after attraction, and repulsion to that of the repulsion, coalescence, and attraction, respectively. Furthermore, within the range of the main resonance radius and the 1/2 order subharmonic resonance radius, the chaotic bubble pairs with alternating attractive and repulsive forces appear in the region between the coalescence pairs and stable pairs after attraction. Finally, the corresponding physical mechanisms of the chaotic translational motions are also revealed.     

高速流场气动光学RANS/DSMC混合数值模拟算法研究

提出了适用于高速流场气动光学数值模拟的RANS/DSMC混合算法.通过RANS对全局时均流场进行数值模拟,再对其中局部流场的脉动量采用DSMC进行数值模拟,以Maxwellian速度分布实现RANS宏观量信息向DSMC微观量信息的传递.采用超声速环境下尖劈模型对该混合算法进行校验,对比试验结果论证了算法的正确性.在计算...     

A nonlinear analysis framework for bluff-body aerodynamics: A Volterra representation of the solution of Navier-Stokes equations

A nonlinear analysis framework for bluff-body aerodynamics based on Volterra theory is introduced to capture the linear and nonlinear aerodynamic effects. The Volterra kernels based on the impulse function concept are identified by way of the simulation of Navier-Stokes equations using computational fluid dynamics (CFD). The computational schemes used here are validated through theoretical consideration, i.e., Blasius solution for the steady-state and Theodorsen solution for the system dynamic-state simulation. The source of nonlinearities in the aerodynamics of bluff bodies is systematically investigated. The simulation of bluff-body aerodynamics based on the Volterra reduced-order modeling scheme is obtained by the convolution of the identified kernels with the external inputs, e.g., turbulent inflow or body motion for aerodynamic or aeroelastic response, respectively. It is demonstrated that the Volterra theory-based nonlinear analysis framework for bluff-body aerodynamics combined with the identification of kernels using CFD promises to capture the salient features of bluff-body aerodynamics and offers an accurate reduced-order approximation of the Navier-Stokes equations with reduced level of computational effort.     

用于板料成形反向模拟的特殊应力更新算法

提出了一种改进的反向模拟法,以最终构型为研究对象,采用Euler坐标系,基于虚功原理获得有限元列式. 改进的反向模拟法采用了一种基于塑性流动理论的本构方程,可以充分考虑应变历史对塑性变形的影响. 为了避免流动理论应力更新算法过程中关于未知量\Delta\lambda 的非线性方程的求解,引入等效应力思想,无需Newton-Raphson迭代直接计算未知量\Delta \lambda . 盒形件的拉深实例中,传统的基于塑性形变本构方程的反向模拟法和改进的基于塑性流动本构方程的反向模拟法计算结果,分别与基于增量有限元法的正向数值模拟求解器LS-DYNA计算结果进行对比. 通过获得的坯料轮廓、成形极限图、等效应变分布、计算效率等的比较,验证了所提出的基于塑性流动理论本构模型的应力更新算法的有效性.      

利用图的完形刻画wsr1条件

本文证明了：对于拟投射右R-模M,End_R（M）满足wsr1条件（即弱的stable range one条件）当且仅当M_R是T-投射模;wsr1条件是左右对称的;对于von Neumann正则环R,R满足wsr1条件当且仅当R为单侧幺正则环．     

Extracellular release of a recombinant gene product by osmotic shock from immobilized microalga in electroconductive membrane

The unicellular blue green alga Synechococcus was immobilized in an electroconductive membrane of polypyrrole-agarose. The Synechococcus was recombinant with a plasmid vector encoding the ampicillin resistance gene. The gene product β-lactamase, a periplasm enzyme of Escherichia coli, was released to medium repeatedly by osmotic shocks. The immobilized cells were stable for over a month and kept their viability under electrical potentials from −0.5 V to 0.6 V vs. Ag/AgCl.     

弱锥2有效集连通性的一个等价定理

利用连通集上有关上半连续点集映射的连通性质，本文证明了拓扑向量空间中向量最优化问题的弱锥－有效解集与相应目标空间中的弱锥－有效点集连通性之间的一个等价定理．     

基于变参数模型的中国能源消费经济增长关系研究

本文利用1953—2002年的统计数据和状态空间模型对中国能源消费与经济增长关系进行了研究。我们的结论是:(1)中国能源消费与经济增长之间存在一种随时间不断变化的长期均衡关系即变参数协整关系;(2)基于状态空间模型的变参数估计很好地揭示了中国能源消费弹性的时变规律。