Singular parameters for the Birman–Murakami–Wenzl algebra

In this paper, we classify the singular parameters for the Birman–Murakami–Wenzl algebra over an arbitrary field. Equivalently, we give a criterion for the Birman–Murakami–Wenzl algebra being Morita equivalent to the direct sum of the Hecke algebras associated to certain symmetric groups.     

Effects of titanium silicalite and TiO2 nanocomposites on supported Co‐based catalysts for Fischer–Tropsch synthesis

Titanium silicalite (TS) and TiO₂ nanocomposites were prepared by mixing TS and TiO₂ with different ratios in ethanol. They were impregnated with 15 wt% Co loading to afford Co‐based catalysts. Fischer–Tropsch synthesis (FTS) performance of these TS–TiO₂ nanocomposite‐supported Co‐based catalysts was studied in a fixed‐bed tubular reactor. The results reveal that the Co/TS–TiO₂ catalysts have better catalytic performance than Co/TS or Co/TiO₂ each with a single support, showing the synergistic effect of the binary TS–TiO₂ support. Among the TS–TiO₂ nanocomposite‐supported Co‐based catalysts, Co/TS–TiO₂‐1 presents the highest activity. These catalysts were characterized using N₂ adsorption–desorption measurements, X‐ray diffraction, X‐ray photoelectron spectroscopy, H₂ temperature‐programmed reduction, H₂ temperature‐programmed desorption and transmission electron microscopy. It was found that the position of the active component has a significant effect on the catalytic activity. In the TS–TiO₂ nanocomposites, cobalt oxides located at the new pores developed between TS and TiO₂ can exhibit better catalytic activity. Also, a positive relationship is observed between Co dispersion and FTS catalytic performance for all catalysts. The catalytic activity is improved on increasing the dispersion of Co.     

Responsive Janus Cage Reactor

A Janus silica cage was synthesized by selectively grafting an ionic liquid (IL) and poly‐N‐isopropylacrylamide (PNIPAM) (lower critical solution temperature (LCST)≈32 °C) onto the exterior and interior sides of the mesoporous SiO₂ shell. The paramagnetic core inside the cavity is responsible for magnetic collection. The PW₁₂O₄₀^3? anion is further conjugated onto the IL side by anion exchange. The Janus cage acts as a thermal‐responsive reactor for catalytic oxidization of dibenzothiophene (DBT) in the presence of H₂O₂. The sulfide in the model oil can be completely decomposed at 25 °C, whilst the oxidative products are more dissoluble in water and preferentially captured inside the Janus cage. The Janus cage reactor could be regenerated at high temperature above 32 °C after releasing the products.     

刺鳅性染色体的细胞遗传学确定证据

通过对刺鳅有丝分裂中期染色体的核型、Ａｇ－ＮＯＲｓ和Ｃ－带分析,以及对精母细胞减数分裂粗线期二价体配对行为的系统观察,确定刺鳅具有一对异配的大型性染色体,其性别决定属ＸＸ／ＸＹ型     

反射激波冲击重气柱的RM不稳定性数值研究

数值研究了二维气柱在入射激波以及反射激波作用下的Richtmyer-Meshkov(RM)不稳定性发展规律, 采用有限体积法结合网格自 适应技术的VAS2D程序, 精确刻画激波和界面的演化. 入射平面激波的马赫数为1.2, 气柱界面内气体为六氟化硫(SF₆), 环境气体为空气, 激波管的尾端为固壁. 通过改变气柱与尾端之间的距离调节反射激波再次作用已经变形的气柱的时间, 获得不同时刻下已经变形的气柱形态、界面尺寸以及环量演化受到反射激波的影响. 结果表明, 反射激波再次作用气柱时, 气柱所处发展阶段不同, 界面演化规律以及环量随时间的变化也不相同, 反射激波与气柱相互作用过程中的涡量产生和分布与无反射情况差异较大, 揭示了不同情况下界面演化的物理机理.     

圆柱壳在两种非轴对称同步移动载荷作用下的动力响应

论文根据工程实例计算的需要,研究了有限长弹性圆柱薄壳在两种非轴对称同步移动载荷作用下的动力响应问题.两种非轴对称同步移动载荷作用是指非轴对称移动的集中载荷,以及同步移动且作用范围随移动位置增加的均布载荷的共同作用.建立了在上述两种不同类型载荷作用下的具有对称形式的动力学微分方程组;分别采用Dirac函数与Heaviside函数表示移动的均布载荷与集中载荷,设定位移函数的基础上,应用Galerkin法及Laplace变换,求得了圆柱薄壳应力与位移动态响应的解析解;通过具体算例,将所得到解析解的计算结果与ANSYS数值解进行了对比分析,验证了解析解的可靠性.     

二阶非自伴两点边值问题Galerkin有限元后处理超收敛解答计算的EEP法

将一维Ritz有限元法超收敛计算的EEP(单元能量投影)法推广到二阶非自伴常微分方程两点边值问题Galerkin有限元法的超收敛计算。在对精确单元的研究中,发现与Ritz有限元法不同,只要检验函数采用伴随算子方程的解,无论试函数取何形式,在结点处都可得到精确的解函数值。对近似单元的研究表明,EEP法同样适用于Galerkin有限元法,不仅保留了简便易行、行之有效、效果显著的特点,同时也保留了EEP法的特有优点,如:任一点的导数和解函数的误差与结点值的误差具有相同的收敛阶。     

Self-adaptive strategy for one-dimensional finite element method based on EEP method with optimal super-convergence order

Based on the newly-developed element energy projection （EEP） method with optimal super-convergence order for computation of super-convergent results, an improved self-adaptive strategy for one-dimensional finite element method （FEM） is proposed. In the strategy, a posteriori errors are estimated by comparing FEM solutions to EEP super-convergent solutions with optimal order of super-convergence, meshes are refined by using the error-averaging method. Quasi-FEM solutions are used to replace the true FEM solutions in the adaptive process. This strategy has been found to be simple, clear, efficient and reliable. For most problems, only one adaptive step is needed to produce the required FEM solutions which pointwise satisfy the user specified error tolerances in the max-norm. Taking the elliptical ordinary differential equation of the second order as the model problem, this paper describes the fundamental idea, implementation strategy and computational algorithm and representative numerical examples are given to show the effectiveness and reliability of the proposed approach.     

有限元线法通用程序——FEMOL92

介绍了用于线弹性结构分析的有限元线法通用程序—FEMOL92。     

Homotopy analysis solution for micropolar fluid flow through porous channel with expanding or contracting walls of different permeabilities

The flow of a micropolar fluid through a porous channel with expanding or contracting walls of different permeabilities is investigated. Two cases are considered, in which opposing walls undergo either uniform or non-uniform motion. In the first case,the homotopy analysis method (HAM) is used. to obtain the expressions for the velocity and micro-rotation fields. Graphs are sketched for some parameters. The results show that the expansion ratio and the different permeabilities have important effects on the dynamic characteristics of the fluid. Following Xu's model, in the second case which is more general, the wall expansion ratio varies with time. Under this assumption, the governing equations are transformed into nonlinear partial differential equations that can also be solved analytically by the HAM. In the process, both algebraic and exponential models are considered to describe the evolution of α(t) from the initial state α0 to the final state α1. As a result, the time-dependent solutions are found to approach the steady state very rapidly. The results show that the time-dependent variation of the wall expansion ratio can be ignored because of its limited effects.