Synchronous collaboration of virtual and remote laboratories

Virtual and remote laboratories(VRLs) are e-learning resources which enhance the accessibility of experimental setups providing a distance teaching framework which meets the student's hands-on learning needs. In addition, online collaborative communication represents a practical and a constructivist method to transmit the knowledge and experience from the teacher to students, overcoming physical distance and isolation. Thus, the integration of learning environments in the form of VRLs inside collaborative learning spaces is strongly desired. Considering these facts, the authors of this document present an original approach which enables user to share practical experiences while they work collaboratively through the Internet. This practical experimentation is based on VRLs, which have been integrated inside a synchronous collaborative e-learning framework. This article describes the main features of this system and its successful application for science and engineering subjects.

Sequential and parallel synchronous alternating iterative methods

The so-called parallel multisplitting nonstationary iterative Model A was introduced by Bru, Elsner, and Neumann [Linear Algebra and its Applications 103:175-192 (1988)] for solving a nonsingular linear system Ax = b using a weak nonnegative multisplitting of the first type. In this paper new results are introduced when A is a monotone matrix using a weak nonnegative multisplitting of the second type and when A is a symmetric positive definite matrix using a P -regular multisplitting. Also, nonstationary alternating iterative methods are studied. Finally, combining Model A and alternating iterative methods, two new models of parallel multisplitting nonstationary iterations are introduced. When matrix A is monotone and the multisplittings are weak nonnegative of the first or of the second type, both models lead to convergent schemes. Also, when matrix A is symmetric positive definite and the multisplittings are P -regular, the schemes are also convergent.

Entre économie de la fonctionnalité et monopole : la United Shoe Machinery Company dans la première moitié du XXe siècle

L’histoire de la United Shoe Machinery Company (USMC) montre que la réalité ne s’adapte pas toujours aux simplifications de la théorie. Comme le signale l’économie de la fonctionnalité, la stratégie de l’entreprise de vendre l’usage plutôt que la machine fournit plusieurs avantages importants, mais elle a également contribué au fait que les usines de chaussures subissent une véritable dépendance technologique de cette compagnie et au fait que l’USMC soit parvenue à une domination monopolistique du marché. D’autre part, en remettant en cause les rudiments généraux de la théorie économique néoclassique, cette position de monopole n’a pas empêché que l’entreprise ait un fonctionnement efficace et ait facilité la modernisation technologique de l’industrie de la chaussure, aux États-Unis et dans d’autres pays.