Narrow Results

In this paper, we study the problem of reducing the energy consumption for hard real-time systems scheduled according to either fixed-priority (FP) or earliest-deadline-first (EDF) scheme. To balance the static and dynamic energy consumptions, the concept of critical speed was proposed in previous research. Moreover, when combined with the processor idle/shutdown state, the critical speed was widely used as the lower bound for voltage scaling in literature. In this paper, we show that this strategy might not always be more energy efficient than the traditional DVS strategy and there exists a dynamic tradeoff between these two strategies depending on the job’s work-demand to be finished within certain intervals. To effectively address this issue, we propose a unified approach that combines these two strategies to achieve better overall energy saving performance. Our approach determines the energy-efficient speeds for real-time jobs in their corresponding feasible intervals based on the threshold work-demand analysis. Our experimental results demonstrate that the proposed techniques significantly outperform previous approaches in the overall energy saving performance.

We consider a dynamic contribution game in which a group of agents collaborates to complete a public project. The agents exert efforts over time and get rewarded upon completion of the project, once the cumulative effort has reached a pre-specified level. We explicitly derive the cooperative solution and a noncooperative Markov-perfect Nash equilibrium. We characterize the set of socially efficient projects, i.e., projects that cooperative groups find worth completing. Comparing with the Markov-perfect Nash equilibrium, we find that noncooperative groups give up large socially efficient projects. Moreover, they take too much time to complete the projects that they undertake.

We conducted a randomized experiment targeting 322 Japanese high school students to examine the impacts of a newly developed English-language learning program. The treated students were offered an opportunity to communicate for 25 minutes with English-speaking Filipino teachers via Skype several times a week over a 5-month period as an extracurricular activity. The results show that the Skype program increased the interest of the treated students in an international vocation and in foreign affairs. However, the students did not improve their English communication abilities, as measured by standardized tests, probably because of the program's low utilization rate. Further investigation showed that the utilization rate was particularly low among students demonstrating a tendency to procrastinate. These results suggest the importance of maintaining students’ motivation to keep using such information and communication technology-assisted learning programs if they are not already incorporated into the existing curriculum. Having procrastinators self-regulate may be especially crucial.

We consider a dynamic contribution game in which a group of agents collaborates to complete a public project. The agents exert efforts over time and get rewarded upon completion of the project, once the cumulative effort has reached a pre-specified level. We explicitly derive the cooperative solution and a noncooperative Markov-perfect Nash equilibrium. We characterize the set of socially efficient projects, i.e., projects that cooperative groups find worth completing. Comparing with the Markov-perfect Nash equilibrium, we find that noncooperative groups give up large socially efficient projects. Moreover, they take too much time to complete the projects that they undertake.