Collective effects at frictional interfaces

We discuss the role of the long-range elastic interaction between the contacts inside an inhomogeneous frictional interface. The interaction produces a characteristic elastic correlation length $\lambda_c = a^2 E / k_c$ (where $a$ is the distance between the contacts, $k_c$ is the elastic constant of a contact, and $E$ is the Young modulus of the sliding body), below which the slider may be considered as a rigid body. The strong inter-contact interaction leads to a narrowing of the effective threshold distribution for contact breaking and enhances the chances for an elastic instability to appear. Above the correlation length, $r > \lambda_c$, the interaction leads to screening of local perturbations in the interface, or to appearance of collective modes --- frictional cracks propagating as solitary waves

Digital storytelling tool for education: An analysis of comic authoring environments

The adoption of interactive digital storytelling environments for learner-generated comics development has been established by prior researchers.As a powerful visual storytelling medium, the literature on comics in education often emphasizes on their affective and cognitive benefits.However, there have been a deficiency of studies that evaluates existing digital comic authoring tools for achieving defined learning goals.Therefore, this paper aims to outline the dimension of several digital comic authoring systems based on Dimension Star reference model. Five digital comic authoring tools are analyzed which are Bitstrips, Comic Life, Pixton, MakeBeliefComix, and Cambridge University Comic Builder.By categorizing comic authoring tool components using the criteria defined by the digital storytelling environment evaluation framework, this paper’s findings provide options and opportunities for educators in selecting appropriate interactive digital storytelling application to facilitate learner-generated comic projects