42 research outputs found
MUTATIONS ET MOUVEMENTS : QUELLE STRATĂGIE GAGNANTE DANS UN ENVIRONNEMENT TURBULENT? UNE ANALYSE DE DEUX ACTEURS ALGĂRIENS INSTALLES A LA LUMIĂRE DE LEURS COMPORTEMENTS ET ATTITUDES
L'observation de lâaccĂ©lĂ©ration des mutations de lâenvironnement dans la plupart des secteurs, vient remettre en question les approches classiques de la stratĂ©gie dâentreprise. A ce titre, lâobjet de cet article est de rĂ©pondre aux divergences sur lâaptitude stratĂ©gique Ă adopter dans ces environnements Ă©volutifs. Le terrain de rĂ©fĂ©rence est celui du marchĂ© des produits laitiers frais en AlgĂ©rie. La recherche est centrĂ©e sur une comparaison entre les actions de deux acteurs Ă©tablis. Les rĂ©sultats montrent que la firme perturbatrice a su tirer profit de son comportement agressif, ce qui lui a mĂȘme permis, dâabsorber lâacteur passif. Il ressort que la stratĂ©gie de perturbation semble ĂȘtre un choix stratĂ©gique performant voire vital pour les entreprises existante
Segmental dynamics and the correlation length in nanoconfined PMMA
We studied the segmental dynamics of poly(methyl methacrylate) (PMMA) in multi-layered films with polycarbonate (PC) having layer thicknesses as small as 4 nm. Such a design provides macroscopic dimensions enabling macroscopic measurements, while maintaining nm-scale confinement. Of particular significance, we were able to determine correlation length scales for the polymer under nanoconfinement. Increases of the local segmental relaxation time, ta, and glass transition temperature, Tg, were observed with decreasing layer thickness. However, neither the fragility (Tg-normalized temperature dependence of ta) nor the breadth of the relaxation dispersion were affected by the geometric confinement. More significantly, the dynamic correlation volume, a measure of the degree of cooperativity of the dynamics, was also unaffected; that is, values of the correlation volume for confined PMMA were equal to those of the bulk polymer when compared at the same ta-. This absence of an effect of geometric confinement on dynamic correlation, even when the confinement length scale approaches the correlation length scale, suggests a nonspherical correlation volume. The slowing of the segmental dynamics of PMMA confined to thin layers is due to admixing of the high Tg polycarbonate. A negligible mixing enthalpy gives rise to an extended interfacial region, which comprises a significant fraction of each layer
Lâadaptation de la gestion intĂ©grale de la qualitĂ© aux prĂ©alables culturels : Ă©tude quantitative des entreprises algĂ©riennes
La gestion de la qualitĂ© totale est une nouvelle approche de penser qui concerne la gestion des organisations d'entreprises qui est basĂ©e sur un ensemble de principes qui peuvent ĂȘtre appliquĂ©es par toute organisation en vue d'atteindre l'efficacitĂ©, lâamĂ©lioration de la productivitĂ©, lâaugmentation des profits et l'amĂ©lioration de sa rĂ©putation sur le marchĂ© local et Ă©tranger. Le TQM est basĂ© sur l'engagement total de la haute direction, la gestion participative, la concentration sur le client et une culture spĂ©cifique, En effet, pas mal dâauteurs ont imputĂ© Ă la rĂ©ussite ou lâĂ©chec de la dĂ©marche de la qualitĂ© totale Ă son adaptation aux dimensions culturelles Le but de cet article est de dĂ©terminer l'impact de la culture organisationnelle âbasant sur les dimensions dâHofstede- sur la rĂ©alisation de la qualitĂ© totale. Pour rĂ©aliser cet objectif, nous avons distribuĂ© une sĂ©rie de questionnaires sur un Ă©chantillon de (50) entreprises algĂ©riennes, nous avons rĂ©cupĂ©rĂ© (31) questionnaires adaptĂ©s Ă lâanalyse
Etude de la mobilité moléculaire dans les systÚmes amorphes complexes : multicouches de polycarbonates de bisphénol A (PC) / polyméthacrylate de méthyle (PMMA) de l'échelle microscopique à l'échelle nanoscopique
Ce travail est consacré à l'étude de la mobilité moléculaire de liquide formateur de verre dans trois zones de température différentes : dans le liquide froid (Tcrossover >T>Tg), autour de la transition vitreuse (T=Tg) et dans l'état vitreux (TT>Tg), around the glass transition and in the vitrous state. In the firstt temperature range, the study of the evolution of molecular mobility was carried out on a model amorphous polymer, the bisphenol polycarbonate A (PC) since the appearance of the cooperativity phenomenon for T=Tcrossover until the glass transition. This was possible by combining two techniques, the TM-DSC and DDS using the theorem of fluctuation dissipation of Callen-Welton. Around the glass transition, we studied a more complex amorphous system, multi-layered films of PC/PMMA with thicknesses varying of the microscopic scale to nanoscopic scale. This enabled the identification of the influence of some parameters on molecular mobility such as the effect of confinement, the juxtaposition of 2 polymers with different chemical structures, the nature of cooperative movements in each polymer and the influence of the interdiffusion zones on the dynamics of the chains. In the vitreous state, the study of physical ageing has been realized for each amorphous polymer constituting our multi-layered films. This phenomenon was studied first considering its dynamic aspect, following the evolution of the enthalpic loss during time by DSC, then considering its dynamic aspect, following the evolution of the dynamic glass transition by TM-DSC. The whole results show the very different behaviour from the two polymers and the huge modification of the physical ageing process in the PC layers at the nanometer scale.ROUEN-BU Sciences Madrillet (765752101) / SudocSudocFranceF
Correction to: Physical aging of multilayer polymer filmsâinfluence of layer thickness on enthalpy relaxation process, effect of confinement
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Physical aging of multilayer polymer filmsâinfluence of layer thickness on enthalpy relaxation process, effect of confinement
International audienc
Physical aging of multilayer polymer filmsâinfluence of layer thickness on enthalpy relaxation process, effect of confinement
International audienc
Correction to: Physical aging of multilayer polymer filmsâinfluence of layer thickness on enthalpy relaxation process, effect of confinement
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Physical and rheological properties of biodegradable poly(butylene succinate)/Alfa fiber composites
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Physical and rheological properties of biodegradable poly(butylene succinate)/Alfa fiber composites
International audienc