This article presents a stochastic dynamic programming model for a condition-based maintenance application. The approach seeks to determine the most opportune moment to inspect and execute preventive maintenance over each component of a nonredundant system, where the number of inspections to be performed simultaneously during each period is limited due to resource constraints. The model minimizes the total maintenance cost per unit of time, considering failure, maintenance, and inspection costs. Unlike most related literature, the model proposed herein allows nonperiodic inspections; it does not require to predefine a maintenance threshold and does not necessarily connect inspections to maintenance actions. Also, the criticality of each component is not static through time, or defined beforehand, but dynamically determined according to the available resources and the risk of failure. A numerical example illustrates the performance of the proposed model in comparison to three traditional maintenance models, namely corrective maintenance, age-based maintenance, and condition-based maintenance with periodic inspections. Results suggest that the proposed model yields the best solution among the studied policies and is more efficient, with a significant reduction of 90% in inspection resources.

The high-penetration of information and communication technologies in our daily activities renews the question about the type of skills learners need to develop on the 21st century. Seeking to foster the development of new media literacies skills in the classroom, we developed Collboard. The Collboard approach combines a pedagogical rationale based on a collaborative strategy aiming at solving open-ended tasks and a technological workflow that incorporates the notion of seamless interactions across different kind of media. Collboard integrates digital pens to support individual work and interactive whiteboards as a collaborative knowledge construction space. We report on the conception of Collboard, its different technological and software components, as well as our initial findings from the experiences we conducted in a Swedish school with 7th grade students in the field of mathematics. Our qualitative observations and initial results provide some indications that this type of learning environments can support the development of new media literacies skills such as collective intelligence, distributed cognition, transmedia navigation and visualization.