Les enjeux économiques de ľinterconnexion des réseaux

The network interconnection and its regulation consist in solving the following dilemma: increase competition and preserve the universal service through access charges, which symbolizes today institutional organization within the telecommunication industry. This paper presents some of the economic and social factors that drive the interconnection policies namely ona (open network architecture) in the United States, or onp (open network provision) in Europe. In the first section, we list some social and economical issues related to open network policies. In the second section, we study the different answers brought up by the regulator through alternative interconnection price formulas. In conclusion, we discuss the stakes and risks of interconnection, while the technological evolution of network introduces intelligent software in switching équipement and implements the tremendous abilities of the digital broadband networks.     

Reading handwritten digits: a ZIP code recognition system

A neural network algorithm-based system that reads handwritten ZIP codes appearing on real US mail is described. The system uses a recognition-based segmenter, that is a hybrid of connected-components analysis (CCA), vertical cuts, and a neural network recognizer. Connected components that are single digits are handled by CCA. CCs that are combined or dissected digits are handled by the vertical-cut segmenter. The four main stages of processing are preprocessing, in which noise is removed and the digits are deslanted, CCA segmentation and recognition, vertical-cut-point estimation and segmentation, and directly lookup. The system was trained and tested on approximately 10000 images, five- and nine-digit ZIP code fields taken from real mail     

Extending the Kernighan/Lin Heuristic for Hardware and Software Functional Partitioning

The Kernighan/Lin graph partitioning heuristic, also known as min-cut or group migration, has been extended over several decades very successfully for circuit partitioning. Those extensions customized the heuristic and its associated data structure to rapidly compute the minimum-cut metric central to circuit partitioning; as such, those extensions are not directly applicable to other problems. In this paper, we extend the heuristic for functional partitioning, which in turn can solve the much investigated codesign problem of partitioning a system's coarse-grained functions among hardware and software components. The key extension customizes the heuristic and data structure to rapidly compute execution-time and communication metrics, crucial to hardware and software partitioning, and leads to near-linear time-complexity and excellent resulting quality. Another extension uses a new criteria for terminating the heuristic, eliminating time-consuming and unnecessary fine-tuning of a partition. Our experiments demonstrate extremely fast execution times (just a few seconds) with results matched only by the slower simulated annealing heuristic, meaning that the extended Kernighan/Lin heuristic will likely prove hard to beat for hardware and software functional partitioning.     

Left ventricular outflow tract obstruction after mitral valve replacement

A method of posterior mitral annulus remodeling is presented. The posterior annulus is divided into three segments, each segment encircled by a suture that is passed in a tourniquet. Coaptation of the leaflets can be achieved by tightening the tourniquets while the ventricle is being filled. This technique is simple and quick, avoids the use of foreign material, and requires less expertise and judgment than traditional annuloplasties.     

Seroepidemiologic indicators for the evaluation of campaigns for the control of foot-and-mouth disease

A sero-epidemiological survey was conducted in two districts in Argentina between 1993 and 1995, to provide additional information on the epidemiology of foot and mouth disease (FMD) in Argentina and to assess the level of immunity in cattle populations, and the circulation of FMD virus. As part of the final stage of this survey, a comparison was made of the results obtained by the enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion techniques. Levels of population immunity against the four types of virus included in the vaccine increased progressively during the period of the survey until, in 1995, at the end of the vaccination period, the percentage of animals possessing adequate levels of protection was approximately 77% in yearlings, and more than 94% in cattle over one year old. During the three-year study, there was a clear tendency for viral activity to diminish, until in 1995 when between 3% and 0.6% were positive to the agar gel immunodiffusion test for the antigen associated with viral infection. By contrast, the ELISA detected antibody in about five times as many animals. The authors show how the increase in the level of population immunity was accompanied by a fall in viral activity.     

Hydrogen-assisted cracking

This article reviews a number of case studies involving hydrogen-assisted cracking in steels. Before the case studies are presented, the current state of understanding of hydrogen-assisted cracking is briefly reviewed. At present there are two leading approaches to the development of a mechanism of hydrogen-assisted cracking, one based upon bond weakening, and the other upon strain localization. As the case studies illustrate, hydrogen-assisted cracking can lead to failures in perhaps unexpected circumstances. The need for the wider dissemination of information about hydrogen cracking to design engineers is indicated.     

Effects of interstitial oxygen on microstructure and mechanical properties of Ti-48Al-2Cr-2Nb with fully lamellar and duplex microstructures

The effect of added oxygen in the range of 1000 to 4000 wt ppm on the microstructures of a Ti-48Al-2Cr-2Nb alloy has been investigated and compared to the microstructures for a high-purity alloy. For specimens cooled from theα phase, interstitial oxygen stabilizes the lamellar microstructure with respect toγ grains, with higher than equilibrium values for theα ₂ volume fraction. For specimens cooled from theα +γ phase field, the lamellar microstructure still tends to be favored by oxygen, but it is found that the phase volume fractions are not significantly different from equilibrium values. This suggests that interstitial O essentially reduces the kinetics of theα toα +γ transformation. Thus, interstitial oxygen will have a strong effect on microstructures obtained by continuous cooling fromα, but significantly less on those, such as the duplex microstructure, obtained by long treatment in theα +γ phase field. In general, increased O content is well correlated with reduced ductility. Finally, the role of interstitial oxygen on this phase transformation is discussed.