媒体网关控制技术及其在Alcatel 5020 MGC中的应用

分析了目前公用交换电话网(PSTN)中存在的问题和下一代网络(NGN)的优越性,分析了NGN中的关键技术媒体网关控制技术,探讨了媒体网关控制技术在Alcatel5020MGC中的实际应用,讨论了Alcatel5020MGC的软硬件系统架构。最后强调了在PSTN向NGN发展过程中基于演进产品的方法的重要性。     

Eigenvalue approach to study the effect of rotation and relaxation time in generalized magneto-thermo-viscoelastic medium in one dimension

The fundamental equations of the problems of generalized thermoelasticity with one relaxation parameter including heat sources in infinite rotating magneto-thermo-viscoelastic media have been derived in the form of a vector matrix differential equation in the Laplace transform domain for a one dimensional problem. These equations have been solved by the eigenvalue approach to determine deformations, stress, and temperature. The results have been compared to those available in the existing literature. The graphs have been drawn to show the effect of rotation in the medium.     

Scattering relations for point‐source excitation in chiral media

A spherical electromagnetic wave propagating in a chiral medium is scattered by a bounded chiral obstacle which can have any of the usual properties. Reciprocity and general scattering theorems, relating the scattered fields due to scattering of waves from a point source put in any two different locations are established. Applying the general scattering theorem for appropriate locations and polarizations of the point source we prove an associated forward scattering theorem. Mixed scattering relations, relating the scattered fields due to a plane wave and the far‐field patterns due to a spherical wave, are also established. Copyright © 2005 John Wiley & Sons, Ltd.     

Consolidation around a borehole embedded in media with double porosity under release of geostatic stresses

The paper deals with the stress, displacement, pore and fissure pressures fields induced by the drilling and/or the pressurization of a vertical borehole in a formation of water-saturated porous media with double porosity. The solution includes the boundary condition of non-hydrostatic in situ state of stress. The solid skeleton is assumed to behave as a linearly poroelastic material with compressible constituents. The analytical solution is derived in Laplace’s space and transformed to the time domain using a numerical inversion technique. The histories of pore and fissure pressures are illustrated to show the influence of permeabilities of the pore and fissure systems.     

基于通信信道的视频传输系统的设计

提出了一种利用PCM基群信道进行视频信号传输的方法,介绍了传输系统的工作原理,对视频编码器进行了较为详细的分析,并采用数字信号处理器作控制器,实现了视频信号的实时传输。     

H.323同步控制实现研究

提出并实现了一种H.323多媒体通信系统音视频同步控制算法,算法以正常语音播放为基准,利用H.263码流语法信息,通过调整视频播放帧率实现媒体间同步, 不增加通信冗余度。实际测试结果表明,算法有效地提高了多媒体通信系统音视频媒体同步性能和多媒体的感知服务质量,并已应用于实际多媒体通信系统。     

Exponential averaging for traveling wave solutions in rapidly varying periodic media

Reaction diffusion systems on cylindrical domains with terms that vary rapidly and periodically in the unbounded direction can be analyzed by averaging techniques. Here, using iterated normal form transformations and Gevrey regularity of bounded solutions, we prove a result on exponential averaging for such systems, i.e., we show that traveling wave solutions can be described by a spatially homogenous equation and exponentially small remainders. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Digital volume gratings

An optical element constructed by stacking a set of binary-phase grating sheets can simulate the functions of optically recorded volume gratings. Our electromagnetic numerical study also shows that if one of the grating sheets is replaced by another one with different grating period, power spectrum of the diffracted wave changes completely with extra diffraction orders. This property will claim strong advantage in security document applications. Analysis of alignment error reveals interesting phenomena concerning to how misalignment affects diffraction efficiency.     

Domain decomposition for an asymptotic geological fault modeling

We present in this paper a domain decomposition method to treat faults in geological basin modeling. The particularity of this model is that the faults whose widths are very small in comparison with the basin size, are not characterized as subdomains any more but as interfaces between sedimentary blocks. The originality of this work lies in the formulation of this new fault model and in the definition and the computation of the interface conditions between the subdomains. To cite this article: E. Flauraud et al., C. R. Mecanique 331 (2003).