Hybrid resonance of Maxwell's equations in slab geometry

Hybrid resonance is a physical mechanism for the heating of a magnetic plasma. In our context hybrid resonance is a solution of the time harmonic Maxwell's equations with smooth coefficients, where the dielectric tensor is a non-diagonal Hermitian matrix. The main part of this work is dedicated to the construction and analysis of a mathematical solution of the hybrid resonance with the limit absorption principle. We prove that the limit solution is singular: it consists of a Dirac mass at the origin plus a principal value and a smooth square integrable function. The formula obtained for the plasma heating is directly related to the singularity.     

人工扰动电离层仿真系统的设计与实现

设计并开发了一种人工扰动电离层仿真系统．建立了数值模型，规划出系统总体构造，在实现过程中引入VC、VF混合编程的概念，以达到两种语言优势互补的目的．文中详细论述了VC、VF混合编程对于数据的处理，生成Fortran的动态链接库，以及在VC中调用生成库的技术．通过仿真模拟，得出了电离层加热过程中电子密度、电子温度等随时间演化的规律，及发射电波频率、功率对加热效果的影响．试用证明，该系统有效地模拟了电离层人工扰动的状态，为在我国实施加热工程提供了可靠的科学依据．     

Enhancement of the electrocatalytic O2 reduction on Pt–Fe alloys

The design of high performance cathode electrocatalysts is essential for polymer–electrolyte fuel cells, which are now attracting enormous interest as a primary power source for zero-emission electric vehicles. We have discovered a significant enhancement of electrocatalytic activity of Pt by alloying with Fe, and found a maximum activity at ca. 50% Fe content, which results in 25 times higher activity than pure Pt activity. It was confirmed experimentally at Pt–Fe bulk alloys that the alloy catalyst surface consists of a pure Pt skin-layer (<1 nm in thickness) that is modified in the electronic structure by that of the bulk alloy. The enhancement could be well explained by the 5d-vacancy of the surface, but not by Pt interatomic distance or roughening of the surfaces.     

Cloud point prediction of fuels and fuel blends

The cloud point temperature, the temperature at which the first wax crystals appear in solution, is one of the most important specifications associated with the low temperature behaviour of a fuel. A database of about 80 fuels and fuel blends was collected and used to assess the performance of the three predictive local composition models (Wilson, NRTL and UNIQUAC) for cloud point prediction. The results indicates that Predictive UNIQUAC can predict the cloud points of the fuels within the experimental uncertainty of the measurements. It could thus be a useful tool in the production of fuels both in the design of refining process and the blend of fuels to meet the low temperature specifications.     

Finite element analysis of thermally coupled nonlinear Darcy flows

We consider a coupled system describing nonlinear Darcy flows with temperature dependent viscosity and with viscous heating. We first establish existence, uniqueness, and regularity of the weak solution of the system of equations. Next, we decouple the coupled system by a fixed point algorithm and propose its finite element approximation. Finally, we present convergence analysis with an error estimate between continuous solution and its iterative finite element approximation.© 2009 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2010     

HL-1装置等离子体特性的初步研究

HL-1装置在环向磁场2.3T下运行,获得135kA平衡稳定等离子体,平顶时间160ms。实验表明,环向磁场杂散分量约为纵场的万分之一,导体壳和平衡场基本上能保证等离子体的平衡。观察到的电子温度约500eV,平均电子密度2.8×10~(13)cm~(-3),能量约束时间10ms,有效电荷数小于3,最低稳定运行安全因子2.5,最长放电持续时间1040ms。在对MHD稳定性进行观察的基础上,确定了稳定运行区域;极限密度服从Murakami定标律。     

Optical emission from laser-produced chromium and magnesium plasma under the effect of two sequential laser pulses

Parametric study of optical emission from two successive laser pulses produced chromium and magnesium plasma is presented. The line emission from chromium and magnesium plasma showed an increase by more than six times for double laser pulse excitation than for single-pulse excitation. An optimum increase in emission intensity was noted for inter-pulse delay of ∼2–3 μs for all the elements. The experimental observations were qualitatively explained on the basis of absorption of second laser pulse in the pre-formed (by first laser) coronal plasma by inverse Bremsstrahlung process, which were found responsible for the excitation of more ions and atoms in the plasma. This process starts as the plasma scale length becomes greater than the laser wavelength. This study further indicated the suitability of this technique in the field of elemental analysis