Showing papers by "Tunis University published in 1986"
TL;DR: In this paper, the transient behavior of the main airgap field of an induction machine starting from rest is investigated and the results obtained show the complex movement of the field as a space vector.
Abstract: The present paper deals with the transient behavior of the main airgap field of an induction machine starting from rest. This is often visualized as a revolving field having constant steady-state speed and direction. In this paper the results obtained show the complex movement of the field as a space vector. It is shown that the transient airgap field has a variable speed and amplitude and sometimes moves in the reverse direction. The results are used to explain the occurrence of transient torque reversals and motor operation over synchronous speed.
26 citations
21 citations
TL;DR: This paper presents an integrated relational methodology for software specification, and shows its effectivness when applied to a practical example.
Abstract: The effectiveness of set theoretic concepts for the purpose of software specification is becoming more and more widely recognized. This paper presents an integrated relational methodology for software specification, and shows its effectivness when applied to a practical example.
15 citations
13 citations
TL;DR: In this paper, a direct hot-luminescence spectra for AlSb is presented, attributed to recombination on acceptors of hot electrons photocreated from the heavy and light-hole bands.
Abstract: Direct hot-luminescence spectra for AlSb are presented. The luminescence is attributed to recombination on acceptors of hot electrons photocreated from the heavy- and light-hole bands. The acceptor binding energy and the effective masses of light holes and conduction electrons near \ensuremath{\Gamma} are deduced from the experimental curves: ${E}_{A}$=30\ifmmode\pm\else\textpm\fi{}5 meV; ${m}_{\mathrm{vl}}$=(0.1\ifmmode\pm\else\textpm\fi{}0.1)${m}_{0}$; ${m}_{c}$=(0.14\ifmmode\pm\else\textpm\fi{}0.20)${m}_{0}$. The high degree of circular polarization (${P}_{c}$\ensuremath{\simeq}0.42) shows the anisotropy of the momentum distribution and the correlation between the spin and the momentum of the electrons. The dynamics of the electrons in the \ensuremath{\Gamma} valley in AlSb shows that the shape of the hot luminescence lines is strongly dependent on the efficiency of electron scattering towards the X valleys.
7 citations
01 Jan 1986
TL;DR: In this paper, the authors propose a succession of six phases morphoclimatiques datees par les industries prehistoriques and le C14C, in which sables eoliens, alluvions fines et grossieres, des formes (entaille des oueds) and de la pedogenese permetres permet de proposer, entre 9 500 and environ 2 000 BP, the succession de six phases.
Abstract: L'etude des formations (sables eoliens, alluvions fines et grossieres), des formes (entaille des oueds) et de la pedogenese permet de proposer, entre 9 500 et environ 2 000 BP, la succession de six phases morphoclimatiques datees par les industries prehistoriques et le C14C.
4 citations
TL;DR: The luminescence is interpreted as recombination of hot electrons, with strong momentum anisotropy, on acceptor on acceptors.
Abstract: The weak direct-gap luminescence originating from the \ensuremath{\Gamma} valley of ${\mathrm{GaAs}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{P}}_{\mathrm{x}}$ indirect-gap alloys is observed. Incident energy dependence and polarization correlation of the luminescence with the exciting light are presented. The luminescence is interpreted as recombination of hot electrons, with strong momentum anisotropy, on acceptors. The dynamics of conduction electrons in the \ensuremath{\Gamma} valley can be discussed.
2 citations
TL;DR: In this article, the absorption of neutrons par une lame taillee dans un milieu absorbant and multiplicateur is decriticated comme un phenomene de naissance and de deces.
Abstract: L'absorption des neutrons par une lame taillee dans un milieu absorbant et multiplicateur est decrite comme un phenomene de naissance et de deces Le nombre de neutrons transmis est une variable aleatoire dont la probabilite est solution du systeme d'equations de Chapman-Kolmogorof
1 citations
01 Jan 1986
TL;DR: In this article, the authors discuss a few issues concerned with chemical pollution, such as the unintended, adverse impact on the environment and on public health following long-term low level exposures to chemical products, is growing.
Abstract: Publisher Summary
This chapter discusses a few issues concerned with chemical pollution. Public concern about the unintended, adverse impact on the environment and on public health, following long-term low level exposures to chemical products, is growing. The general public is concerned about the benefits and risks associated with the use of chemicals. Polyvinyl chloride (PVC) is widely used in household products such as bottles, food containers and their plastic wraps. This polymer is now a general contaminant of the planet and the sailor. It must be stressed that many other safe means for controlling pests are now available. It seems valid to ask for a worldwide ban on the use of chlorinated hydrocarbons, these largely outdated chemicals which pollute the whole eco-system. The effects of lead ingestion in large quantities are well documented. Symptoms of lead poisoning include loss of appetite, apathy, weakness and miscarriages. Lead causes lesions of the neuromuscular system, gastrointestinal tract, circulatory system and the brain.
TL;DR: For tout graphe fini connexe G, le maximum m(G) de la dimension de l'espace des fonctions harmoniques est determine par l'spaces des flots and le nombre des composantes 2-arete-connexes extremales de G as mentioned in this paper.
Abstract: Pour tout graphe fini connexe G, le maximum m(G) de la dimension de l'espace des fonctions harmoniques est determine par l'espace des flots et le nombre des composantes 2-arete-connexes extremales de G