Digital Switching in France

This paper intends firstly to present how digital switching was introduced into the French network nearly ten years ago and what are the main advantages brought by digital switching systems. Various cases in the network such as trunk or local exchanges are examined; general as well as particular advantages are shown. Secondly, the technical requirements for these exchanges are described; an emphasis is put on the specific aspects of digital switching. Digital switching systems already in operation or on the verge of being commissioned are outlined. Finally, different tables give information concerning mainly the number of subscriber lines connected to class 3 and 4 digital exchanges by the end of 1978.     

A study of section wrinkling on single-hole coated grids using TEM and SEM

To prevent section wrinkles usually encountered with the use of coated single-hole grids, a simple method was developed. Formvar film resting on a platform with holes (3.5 mm diameter) was heated with a slide warmer (60–65°C). The bottom of a glass petri dish was inverted over the platform to keep the ambient air at the desired temperature. Sections were picked up from the boat of the diamond knife with a single-hole grid and deposited at the orifice of the platform and allowed to dry. The grids were then carefully pushed through the orifice of the platform with the blunt head of a nail (3 mm diameter).     

Radiation damage to lyophilized mineral solutions during electron probe analysis: quantitative study of chlorine loss as a function of beam current-density and sample mass-thickness

The quantitative effects of beam current-density and sample mass-thickness on the loss of chlorine which occurs from lyophilized solutes of micro-droplets of mineral salt solutions irradiated in an electron probe analyser were studied. Results are reported for chlorine loss from lyophilized deposits with mass-thickness varying between 5 and 50 mg mm^?2 for NaCl salts and 5 and 80 mg mm^?2 for KCl salts. Electron accelerating voltage was kept constant at 15 kV. The range of beam current-density (I/S, current/sample surface area) was from 0.1 to 1.5 A mm^?2. Samples were irradiated for 1200 s. The results show that under some conditions there is a period of stable chlorine signal before chlorine loss occurs. This is observed between 0.1 and 1 A mm^?2, for a period which can last several hundred seconds depending on beam current-density and sample mass-thickness. For each value of I/S, however, no stable chlorine signal can be observed for samples whose mass-thickness exceeds a value negatively correlated with I/S. The curves of decrease of characteristic chlorine X-ray signal (expressed as per cent of count rate in the initial counting interval) versus irradiation time can be fitted by the sum of two exponentials with half lives T₁ and T₂. In NaCl, T₁ and T₂ values are highly correlated with I/S but not with mass-thickness. In KCl, T₁ is correlated only with mass-thickness and T₂ only with I/S. Mixing plasma with mineral solutions prevents chlorine loss.     

Germanium,zinc’s important byproduct

A pioneer of germanium as well as Europe’s oldest and largest producer of zinc is Vieille-Montagne. Germanium output is centered at the zinc-lead plant of Balen, Belgium, where it is a byproduct of electrolytic zinc.     

The use of thermal analysis techniques for the validation of phase transformation models

In the study of the phase transformation of steel several methods can be used to obtain information about the behaviour of steel during heating and cooling. In this research several conventional methods, e.g. dilatometry, were studied together with an in-situ thermal analysis method (ISTA). This method, which can be applied to any cooling curve, enables us to draw conclusions as to the transformation behaviour of the steel. Using a continuous annealing simulator (Casim) a range of cooling rates can be investigated with the resulting mechanical properties. It will be demonstrated that ISTA can be performed on the results of a variety of experimental techniques and therefore under very different experimental conditions. It is possible to investigate transformation behaviour and mechanical properties on a single test piece. Using the pressurized air cooling of the Casim proves to be a good compromise between the possibilities of determining the mechanical properties and flexibility in cooling conditions of the specimens.     

The role of mobile organic radicals and ions (solitons,polarons and bipolarons) in the transport properties of doped conjugated polymers

We discuss the formation of charged defects such as solitons, polarons and bipolarons, in doped conjugated polymers. We present the results of ab initio quality calculations on the modifications of geometric and electronic structures occurring upon doping. A transport model for spinless conduction through bipolarons applicable to doped polymers with or without degenerate ground state is described.     

A Framework for Optimizing End-to-End Connectivity Degree in Mobile Ad-Hoc Networks

Mobile ad-hoc networks are networks spontaneously deployed from a set of mobile devices without requiring any fixed infrastructures. The increasing interest in this technology raises new research challenges towards providing them a management framework. Network users expect a service level as close as in regular fixed networks. A primary expectation is the capability to communicate (end-to-end) with the other network users. We present in this paper a framework for monitoring and optimizing this capability in mobile ad-hoc networks. Our normalized metric, called end-to-end connectivity degree, characterizes the number of nodes, that a node can reach in the entire network. We describe a management architecture to monitor this metric together with the network density, and illustrate how routing configuration can be performed to optimize it.     

Relations entre la notion et la perception de la vitesse relative chez l'enfant.

Administered 2 tasks bearing on the perception and concept of relative velocity to 7-, 9-, 11-, and 13-yr-old children (24 at each age level). The perceptual task presented an illusion created by the movement of a target on a moving background, while the conceptual task was a modified version of Piaget's technique. In each task the 2 movements involved were either in the same (MS) or in the opposite direction. It was found that the illusion appeared earlier than the corresponding concept under the MS condition. The possibility of a retroactive effect of the concept on the percept is suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)