A New Numerical Method for Accurate Simulation of Fast Cyclic Adsorption Processes

In the simulation of fast cyclic adsorption processes, to apply the Fickian diffusion model it is necessary to include an increasing number of numerical discretization points as the cycle time is reduced in comparison to the characteristic diffusional time constant. We propose a new numerical method based on the definition of two distinct regions within an adsorbent particle: an outer layer where the concentration varies significantly with large internal gradients leading to enhanced mass fluxes, and an internal region where the concentration profile is virtually flat. The proposed method leads to the automated generation of a numerical grid that has a constant number of elements independent of the process cycle time. The procedure is demonstrated on a model for the simulation of a heatless dryer pressure swing adsorption process.     

Developing and Testing a Microelectrode for Assaying Nitric Oxide

Voltametric studies on glassy-carbon and carbon-fiber electrodes result in the development and testing of a carbon-fiber microelectrode capable of operating in model buffer and biological solutions when monitoring nitric oxide in vivo. The Nafion-modified electrode confidently determines the NO presence in solutions containing anions NO ₂ ^? , which interfere with the assay. Once properly calibrated, it permits quantitative determination of the NO concentration in a buffer solution.     

Tame kernels of cubic cyclic fields

There are many results describing the structure of the tame kernels of algebraic number fields and relating them to the class numbers of appropriate fields. In the present paper we give some explicit results on tame kernels of cubic cyclic fields. Table 1 collects the results of computations of the structure of the tame kernel for all cubic fields with only one ramified prime

In particular, we investigate the structure of the 7-primary and 13-primary parts of the tame kernels. The theoretical tools we develop, based on reflection theorems and singular primary units, enable the determination of the structure even of 7-primary and 13-primary parts of the tame kernels for all fields as above. The results are given in Tables 2 and 3.

     

Stability of Preconditioned Finite Volume Schemes at Low Mach Numbers

A finite volume method for inviscid unsteady flows at low Mach numbers is studied. The method uses a preconditioning of the dissipation term within the numerical flux function only. It can be observed by numerical experiments that the preconditioned scheme combined with an explicit time integrator is unstable if the time step Δt does not satisfy the requirement to be as the Mach number M tends to zero, whereas the corresponding standard method remains stable up to , M → 0, though producing unphysical results. A comprehensive mathematical substantiation of this numerical phenomenon by means of a von Neumann stability analysis is presented, which reveals that in contrast to the standard approach, the dissipation matrix of the preconditioned numerical flux function possesses an eigenvalue growing like M^–2 as M tends to zero, thus causing the diminishment of the stability region of the explicit scheme. The theoretical results are afterwards confirmed by numerical experiments. AMS subject classification (2000) 35L65, 35C20, 76G25     

Response of a Thin Cylindrical Shell Excited by a Turbulent Internal Flow

This paper presents results obtained within the scope of a collaboration between the “Laboratoire de Mécanique et d'Acoustique” (Marseille, France), the “Laboratoire de Mécanique des Fluides et d'Acoustique” of the Ecole Centrale (Lyon, France) and the “Laboratoire de Vibrations et d'Acoustique” of the Institut National des Sciences Appliquées (Lyon, France). The main aspect of this collaboration is to establish a comparison between a measured and a model vibro-acoustics response of a thin cylindrical pipe excited by a turbulent internal flow. After a brief review of the literature, a model of the response of the shell, based on a matched asymptotic expansion, is given. Some numerical results are also given. The spectral density of the acceleration of the shell is compared with experimental results. This revised version was published online in July 2006 with corrections to the Cover Date.     

Noncommutative homology of some three-dimensional quantum spaces

We compute the Hochschild and cyclic homology of certain three-dimensional quantum spaces (type A algebras), introduced by Artin and Schelter. We show that the Hochschild homology is determined by the quasi-classical limit.     

小型化电谐振人工特异材料研究

详细分析了电谐振人工特异材料设计原理,并结合等效电路模型通过加载等效电感、等效电容和接地等方法,将相同尺寸的工字形结构工作频率从12.21 GHz降到了5.46 GHz,小型化效果明显.该成果不仅对于不同结构人工特异材料小型化设计提供了重要的参考,同时也为设计不同性能、不同工作频率的人工特异材料提供了明确的研究方向和有效的途径.