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Due to the importance of power dissipation in the wireless sensor networks and embedded systems, real-time scheduling has been studied in terms of various optimization problems. Real-time tasks that synchronize to enforce mutually exclusive access to the shared resources could be blocked by lower priority tasks. While dynamic voltage scaling (DVS) is known to reduce dynamic power consumption, it causes increased blocking time due to lower priority tasks that prolong the interval over which a computation is carried out. Additionally, processor slowdown to increase execution time implies greater leakage energy consumption. In this paper, a leakage-controlled method is proposed, which decreases both priority inversion and power consumption. Based on priority ceiling protocol (PCP) and a graph reduction technique, this method can decrease more energy consumption and avoid priority inversion for real-time tasks.

In recent years, many emerging information technologies have been applied to learning environments in an attempt to overcome drawbacks associated with traditional teaching environments. Some of these technologies have been shown to improve learning outcomes and learning motivation. Advances in wireless communications have raised research interest in the development of ubiquitous learning (u-learning) environments and their impact on learner attitudes and behavior. This study reports the use of augmented reality (AR) technology to create virtual objects for use in mobile devices to create a context-aware, AR-enabled guided tour application for outdoor learning. The goal is to provide learners with a friendly, interactive interface and rich, engaging media to stimulate intrinsic motivation and learning performance. The main advantages of the proposed system include the following: (1) it helps stimulate learning intention through pursuing outdoor learning objectives, (2) AR technology provides learners with contextual information related to the outdoor learning environment, and (3) it enhances learner retention of teaching contents easily with the situated learning strategy.