Effect of surface structure on the catalytic behavior of Ni：Cu/Al and Ni：Cu：K/Al catalysts for methane decomposition

Methane decomposition using nickel, copper, and aluminum （Ni：Cu/Al） and nickel, copper, potassium, and aluminum （Ni：Cu：K/Al） modified nano catalysts has been investigated for carbon fibers, hydrogen and hydrocarbon production. X-ray photoelectron spectroscopy （XPS）, static secondary ion mass spectrometry （SSIMS）, thermal gravimetric analysis （TGA）, Fourier transform infrared （FT-IR）, secondary electron microscopy/X-ray energy dispersive （SEM-EDX）, and temperature programmed desorption （TPD） were used to depict the chemistry of the catalytic results. These techniques revealed the changes in surface morphology and structure of Ni, Cu, Al, and K, and formation of bimetallic and trimetallic surface cationic sites with different cationic species, which resulted in the production of graphitic form of pure carbon on Ni：Cu/Al catalyst. The addition of K has a marked effect on the product selectivity and reactivity of the catalyst system. K addition restricts the formation of carbon on the surface and increases the production of hydrogen and C2, C3 hydrocarbons during the catalytic reaction whereas no hydrocarbons are produced on the sample without K. This study completely maps the modified surface structure and its relationship with the catalytic behavior of both systems. The process provides a flexible route for the production of carbon fibers and hydrogen on Ni：Cu/Al catalyst and hydrogen along with hydrocarbons on Ni：Cu：K/Al catalyst. The produced carbon fibers are imaged using a transmission electron microscope （TEM） for diameter size and wall structure determination. Hydrogen produced is COx free, which can be used directly in the fuel cell system. The effect of the addition of Cu and its transformation and interaction with Ni and K is responsible for the production of CO/CO2 free hydrogen, thus producing an environmental friendly clean energy.     

Amplitude equations for SPDEs with cubic nonlinearities

For a quite general class of stochastic partial differential equations with cubic nonlinearities, we derive rigorously amplitude equations describing the essential dynamics using the natural separation of timescales near a change of stability. Typical examples are the Swift–Hohenberg equation, the Ginzburg–Landau (or Allen–Cahn) equation and some model from surface growth. We discuss the impact of degenerate noise on the dominant behaviour, and see that additive noise has the potential to stabilize the dynamics of the dominant modes. Furthermore, we discuss higher order corrections to the amplitude equation.     

氨基酸的2,3-二甲醛基喹喔啉荧光衍生及高效液相色谱分离分析

将荧光试剂2,3-二甲醛基喹喔啉首次应用到氨基酸的高效液相色谱分离分析中。考察了该荧光试剂与伯胺氨基酸衍生反应的pH值、比例、反应时间等影响因素,确定衍生反应的最佳条件为:100 mmol/L硼砂缓冲液(pH 9.5),二巯基乙醇、衍生试剂与氨基酸的比例为9∶3∶1,室温下反应5 min。采用C18色谱柱,经二元梯度洗脱,荧光检测,17种伯胺蛋白氨基酸得到较好分离。氨基酸的浓度在0.01～1.00 mmol/L范围内与其衍生物峰面积呈较好的线性关系,氨基酸衍生物的检出限为0.02～0.07μg/L。应用该方法对麦冬中游离氨基酸的含量进行测定,结果满意。此方法快速,高效,灵敏度高,精密度好。     

Logarithmic barrier decomposition-based interior point methods for stochastic symmetric programming

We introduce and study two-stage stochastic symmetric programs with recourse to handle uncertainty in data defining (deterministic) symmetric programs in which a linear function is minimized over the intersection of an affine set and a symmetric cone. We present a Benders’ decomposition-based interior point algorithm for solving these problems and prove its polynomial complexity. Our convergence analysis proved by showing that the log barrier associated with the recourse function of stochastic symmetric programs behaves a strongly self-concordant barrier and forms a self-concordant family on the first stage solutions. Since our analysis applies to all symmetric cones, this algorithm extends Zhao’s results [G. Zhao, A log barrier method with Benders’ decomposition for solving two-stage stochastic linear programs, Math. Program. Ser. A 90 (2001) 507–536] for two-stage stochastic linear programs, and Mehrotra and Özevin’s results [S. Mehrotra, M.G. Özevin, Decomposition-based interior point methods for two-stage stochastic semidefinite programming, SIAM J. Optim. 18 (1) (2007) 206–222] for two-stage stochastic semidefinite programs.     

A new higher‐order accurate numerical method for solving heat conduction in a double‐layered film with the neumann boundary condition

Heat conduction in multilayered films with the Neumann (or insulated) boundary condition is often encountered in engineering applications, such as laser process in a gold thin‐layer padding on a chromium thin‐layer for micromachining and patterning. Predicting the temperature distribution in a multilayered thin film is essential for precision of laser process. This article presents an accurate finite difference (FD) scheme for solving heat conduction in a double‐layered thin film with the Neumann boundary condition. In particular, the heat conduction equation is discretized using a fourth‐order accurate compact FD method in space coupled with the Crank–Nicolson method in time, where the Neumann boundary condition and the interfacial condition are approximated using a third‐order accurate compact FD method. The overall scheme is proved to be convergent and hence unconditionally stable. Furthermore, the overall scheme can be written into a tridiagonal linear system so that the Thomas algorithm can be easily used. Numerical errors and convergence rates of the solution are tested by an example. Numerical results coincide with the theoretical analysis. © 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 1291–1314, 2014     

M_2(R)上的非线性Lie导子

设R是一个含有单位元的2无扰的交换环,M_2(R)是定义在R上的全矩阵代数,证明了M_2(R)上的每一个非线性Lie导子都可以表示成一个内导子,一个可加诱导导子和一个映所有二次换位子为零的中心映射的和.     

Existence,uniqueness and regularity of stationary solutions to inhomogeneous Navier-Stokes equations in ℝ<Superscript><Emphasis Type="Italic">n</Emphasis></Superscript>

For a bounded domain Ω ⊂ ℝ ⁿ , n ⩾ 3, we use the notion of very weak solutions to obtain a new and large uniqueness class for solutions of the inhomogeneous Navier-Stokes system − Δu + u · ∇u + ∇p = f, div u = k, u _|aΩ = g with u ∈ L ^q , q ⩾ n, and very general data classes for f, k, g such that u may have no differentiability property. For smooth data we get a large class of unique and regular solutions extending well known classical solution classes, and generalizing regularity results. Moreover, our results are closely related to those of a series of papers by Frehse & Růžička, see e.g. Existence of regular solutions to the stationary Navier-Stokes equations, Math. Ann. 302 (1995), 669–717, where the existence of a weak solution which is locally regular is proved.      

碳助剂对完全液相法制备的 Cu-Zn-Al 催化剂性能的影响

 采用完全液相法制备了 Cu-Zn-Al 催化剂, 研究了碳纳米管和碳微球的加入对该催化剂 CO 加氢合成低碳醇反应性能的影响, 并用 X 射线粉末衍射、氮气吸附、氢气程序升温还原和氨气程序升温脱附-质谱等方法对催化剂进行了表征. 结果表明, 用完全液相法制备的 Cu-Zn-Al 甲醇合成催化剂具有一定的合成低碳醇和低碳烃的能力, 这种能力归结于较大 Cu0 晶粒的产生. 一定量碳微球的加入可大大减小 Cu0 晶粒度, 从而大幅度提高甲醇选择性.     

CSL代数上的Lie导子

证明了不相关的有限宽度CSL代数上的每一个Lie导子都是内导子与作用在交换子上为零的中心值线性映射之和.