The influence of preparative parameters on the adhesion of alumina washcoats deposited on metallic supports

Well-adhered alumina washcoats on FeCrAl metallic supports were prepared using boehmite sols and alumina slurries. The microstructure and the surface performance of the washcoat/support were investigated by SEM, XRD, and ultrasonic vibration. The effects of the main preparative parameters on the coating adherence were studied. The optimal coating conditions are presented as follows: pre-oxidation of the metallic supports was performed at 900 °C for 10 h, the sol layer loadings were 2.0-6.6 wt.%, and the slurry layer loadings were less than 25.3 wt.%. The sol layer drying was performed at 30 °C for 1 h and that for the slurry layer the drying was performed at 120 °C for 2 h, and the coating calcining was performed at 900 °C for 2 h. The SEM photographs of coated samples show that alumina washcoats were well deposited on the metallic supports.     

Construction of the elliptic Gaudin system based on Lie algebra

Gaudin model is a very important integrable model in both quantum field theory and condensed matter physics. The integrability of Gaudin models is related to classical r-matrices of simple Lie algebras and semi-simple Lie algebra. Since most of the constructions of Gaudin models works concerned mainly on rational and trigonometric Gaudin algebras or just in a particular Lie algebra as an alternative to the matrix entry calculations often presented, in this paper we give our calculations in terms of a basis of the typical Lie algebra, A _n , B _n , C _n , D _n , and we calculate a classical r-matrix for the elliptic Gaudin system with spin.      

基于第一性原理量子输运模拟的并行计算

为了解决基于第一性原理分析计算大尺度量子输运体系时遇到的耗时长久问题,挖掘密度泛函理论与非平衡格林函数相结合方法(DFT+NEGF方法)在自洽迭代过程中的计算热点,就计算电子密度矩阵时的能量点积分和计算格林函数时的矩阵求逆/乘法运算提出MPI/Open MP并行计算方案.能量点积分采用MPI多进程并行方案,在数据初始化时需要将稀疏矩阵和积分能量点依照轮询调度算法分配给各进程.矩阵求逆/乘法的并行化既可调用ScaLAPACK子程序实现又可调用IntelMKL数学库中的OpenMP多线程加速函数实现.由于不同能量点计算的独立性,能量点积分采用的MPI并行计算获得近乎线性的加速比曲线.由于Open MP多线程并行采用的是基于共享内存的数据交换机制以及线程间切换通信开销小,矩阵求逆/乘法运算的OpenMP并行实现在计算效率上要优于而在程序的可扩展性上要劣于MPI多进程并行实现.     

高阶间断伽辽金时域有限元方法分析三维谐振腔

从一阶麦克斯韦旋度方程出发,研究一种区域分解时域有限元目的——高阶间断伽辽金时域有限元目的.其中对时间的离散采用Crank-Nicolson差分格式,电场和磁场采用相同阶数的高阶矢量基函数展开.分析三维谐振腔问题,数值结果表明,目的 中时间步长的选取可以摆脱CFL稳定性条件的限制;此外,与基于常用Whitney矢量基函数的目的 相比,采用高阶矢量基函数可以明显地提高计算精度及计算效率.     

Effect of Finite Rise Time on the Strength of the Magnetic Field Generated in a Switched Plasma

The effect of a magnetized transient plasma on a circularly polarized source wave, when the rise time of the electron density profile is comparable to the source wave period, is considered. The H-formulation Green's function is developed to study the effect of a finite rise time on the generation of a wiggler magnetic field.     

一个用于支持经济预测决策的EP—ESS模型

本文论述了EP-ESS的结构及其各部分之间的关系,并给出了ES部分推理的数学模型及其实现的流程图。     

螺旋型电磁超声辐射声场对缺陷检测影响的 计算机模拟*

电磁超声(EMAT)作为一种非接触超声检测技术,已得到了普遍的关注和研究。然而,EMAT目前只得到了一些有限的应用,尤其在缺陷探伤应用方面还不能替代压电超声,深入探究其原因并加以改进,对推动EMAT在缺陷检测方面的应用具有重要意义。利用有限元方法建立了螺旋型EMAT模型,分析了其辐射声场和声场特征;通过将有限元计算所得到的洛伦兹力分布简化为门函数,并结合格林函数法,得到了螺旋型EMAT辐射声场的简化解析结果。这些方法可用于计算螺旋型EMAT辐射声场指向性以及在缺陷检测中比较关心的一些特征参数,如扩散角、偏离角等参数。通过螺旋型EMAT辐射声场实验,验证了理论分析结果。通过与压电超声检测理论与实验的对比,研究认为：螺旋型EMAT辐射声场的具有横波和纵波等多种波模及多种模态转换的特点,以及相对复杂的异型声场几何分布等复杂特性,使其在缺陷检测应用方面受到局限。这些研究方法对改进EMAT设计,优化控制EMAT辐射声场,拓展EMAT在缺陷检测方面的应用具有参考价值。     

Fano effect of a parallel-coupled triple Rashba quantum dot system

Using the nonequilibrium Keldysh Green's function technique, the Fano effect of a parallel-coupled triple Rashba quantum dot system is investigated. The conductance as a function of electron energy is numerically calculated. Compared with the case of a parallel-coupled double quantum dot system, two additional Fano resonance peaks occur in the conductance spectrum. By adjusting the structural parameters, the two Fano resonance peaks may change into the resonance peaks. In addition, the influence of Rashba spin-orbit interaction on the conductance is studied.     

原子核的单粒子共振态

采用基于相对论平均场的耦合常数解析延拓方法研究球形核的单粒子共振态.具体计算了Zr同位素链中巨晕核的核芯核122Zr阈值附近的中子共振态的能量、宽度和波函数,其结果同相应的散射相移法的结果一致. Using analytic continuation in the coupling constant (ACCC) method within the framework of the self-consistent relativistic mean field (RMF) theory, the energies, widths and wave functions for single-particle resonant states close to the continuum threshold are evaluated. Predictions are also compared with corresponding results obtained by the scattering phase shift method.     

Effect of the structure of nitroxyl radicals on the kinetics of their acid‐catalyzed disproportionation

Acid‐catalyzed disproportionation of cyclic nitroxyl radicals R₂NO^? includes the half‐reactions of their oxidation to oxoammonium cations R₂NO⁺ and reduction to hydroxylamines R₂NOH. For many nitroxyl radicals, this reaction is characterized by its ~100% reversibility. Quantitative characteristics of acid–base and redox properties of the whole redox triad may be obtained from research of kinetics and equilibrium of this reaction. Here, we have examined the kinetics for the disproportionation of twenty piperidine‐, pyrroline‐, pyrrolidine‐, and imidazoline nitroxyl radicals in aqueous H₂SO₄, and interpreted it in terms of the excess acidity function X. The rate‐limiting step of this reaction is R₂NO^? oxidation by its protonated counterpart R₂NOH^+?. Kinetic stability of R₂NO^? in acidic media depends on the basicity of nitroxyl group. This basicity is influenced predominantly by protonation of another, more basic group in radical structure, and its proximity to nitroxyl group. The discovered estimates of pK values for radical cations R₂NOH^+? (from ?5.8 to ?12.0) indicate a very low basicity of nitroxyl groups in all commonly used R₂NO^?. For the first time, a linear correlation is obtained between the one‐electron reduction potentials of oxoammonium cations and the basicity of nitroxyl groups of related radicals. Copyright © 2013 John Wiley & Sons, Ltd.