Application of N,N‐bis(diphenylphosphino)aniline palladium(II) complexes as pre‐catalysts in Heck coupling reactions

Palladium(II) complexes with N,N‐bis(diphenylphosphino)aniline ligands catalyse the Heck reaction between styrene and aryl bromides, affording stilbenes in good yield. The structures of two of the complexes used as pre‐catalysts have been determined by single‐crystal X‐ray diffraction. Copyright © 2007 John Wiley & Sons, Ltd.     

Champ de vitesse dans un échangeur à vortex en régime turbulentHeat exchanger velocity field with turbulent inlet condition

We consider the isothermal flow through a cylindrical flat chamber, a model of some particular heat exchanger, for which LDV measurements and a numerical simulation have been performed. Experimental results show the establishment of an important vortex zone, the secondary flow extending all along the chamber radius. This observation leads to an expected significant increase of the fluid mixing. Results issued from the numerical simulation appear to be in close agreement with experimental data. Nevertheless, the k–ε model used here must be improved to obtain a better approach near the vortex centre. To cite this article: S. Petitot et al., C. R. Mecanique 330 (2002) 593–599.     

Studies on heterocyclic enamines: New syntheses of 4H-pyranes,pyranopyrazoles and pyranopyrimidines

The behaviour of several 2-amino-3-cyano-4H-pyran derivatives toward a variety of nucleophilic reagents is reported.     

基于Web的图书馆管理系统访问控制策略

针对基于Web的图书馆管理系统资源访问控制的动态性问题，提出了一种基于角色的访问控制策略描述方案．通过对基于Web的图书馆管理系统访问控制管理影响因素和访问控制需求的分析，结合NIST基于角色的访问控制统一模型标准，构造了一种基于角色的访问控制元模型．并在这一元模型的基础上，提出了一种紧凑的基于角色的访问控制XML策略描述语言框架．结果表明该访问控制策略描述语言框架适合表述动态环境下对图书馆资源的访问策略，提高了基于Web的图书馆管理系统资源访问的安全性．     

An improved max-flow-based lower bound for minimizing maximum lateness on identical parallel machines

In this paper, we introduce a new concept of semi-preemptive scheduling and we show how it can be used to derive a maximum-flow-based lower bound for the P|r_j|L_max which dominates the well-known preemptive lower bound. We show that, in some cases, the proposed bound strictly dominates the preemptive one while having the same complexity.     

Sinc-Galerkin method for solving linear sixth-order boundary-value problems

There are few techniques available to numerically solve sixth-order boundary-value problems with two-point boundary conditions. In this paper we show that the Sinc-Galerkin method is a very effective tool in numerically solving such problems. The method is then tested on examples with homogeneous and nonhomogeneous boundary conditions and a comparison with the modified decomposition method is made. It is shown that the Sinc-Galerkin method yields better results.

     

Convergence analysis of perturbed hemivariational inequalities

We consider the rate of convergence for a class of perturbed hemivariational inequalities in reflexive Banach Spaces. Our results can be viewed as an extension and refinement of some previous known results in this area.     

A Numerical Calculation for Electron Impact Excitation of Copper

The scattering of electrons by atomic copper has been studied using Born approximation and the concept of the generalized oscillator strength (GOS). Differential and total cross-sections for the excitation of the 3d¹⁰ 4p² P state are calculated at incident energies of 100 eV and are compared with other available experimental and theoretical data. The agreement between our calculation for the differential cross-section and the available experimental results is fairly good at the forward angles, while the agreement at large angles is poor. The calculated total cross-sections are compared with the experimental data and those predicted by several theories. It is found that our calculation for the total cross-sections are in a good agreement with the close coupling calculation of Msezane and Henry (1986a, Physical Review A 33, 1631) for incident energies greater than 20 eV. The integrated cross-section measurements of Ismail and Teubner (1995, Journal of Physics B: Atomic, Molecular and Optical Physics 28, 4164) are in good agreement with the present calculation.     

Existence and boundary behavior for singular nonlinear differential equations with arbitrary boundary conditions

Existence theory is developed for the equation ?(u)=F(u), where ? is a formally self-adjoint singular second-order differential expression and F is nonlinear. The problem is treated in a Hilbert space and we do not require the operators induced by ? to have completely continuous resolvents. Nonlinear boundary conditions are allowed. Also, F is assumed to be weakly continuous and monotone at one point. Boundary behavior of functions associated with the domains of definitions of the operators associated with ? in the singular case is investigated. A special class of self-adjoint operators associated with ? is obtained.