Careful examination of packet traces taken from the MBone reveals a significant number of multiple successive packet losses, even though losses are predominantly isolated. This paper presents a method for reducing the number of burst losses by transforming them into single isolated losses. In this method, the first step is to separate critical video information from noncritical video signals, assuming the availability of an efficient layered coder. Secondly, by exploiting the unordered delivety feature of UDP, packets are interleaved utid randomized so as to spread out the loss of critical video inforniution. Finally, in order to reduce the number of random losses, redundant packets of essential video data are included in the interleavedrandomized packet sequence. To prove the effectiveness of this method, experiments were conducted on packet traces collected from the MBone. Results indicate that interleaving/randomization alone, significantly reduces consecutive packet burst losses. Furthermore, results are even better with the inclusion of essential redundant video datu, which draniatically reduces the number of disjoint losses.' This project is partially funded by CSIRO, an Australian government research organization.
To investigate the reasons for the high failure rates in introductory programming courses, this paper employs a case-study approach to explore the integration of context of learning, conceptions of learning, and approaches to study. Students' responses show that their approaches to study are directly related to the context and conceptions of learning. Five concepts of learning are illustrated through two models proposed by previous studies. These concepts are then used as benchmarks for comparing with the concepts of the case studies to investigate these students' approaches to learning. It is found that students with intrinsic interest and are academically orientated automatically adopt the deep approach to learning whilst academically orientated students with extrinsic interest can adopt the deep approach only with help from institutional context. Accordingly, this paper proposes a practical teaching / learning model to help students to attain the deep approach to study. Implemented this semester, to date the model has changed students' orientation to study, as well as encouraged some students towards the deep approach to study.Index Terms -Approaches to study, conceptions of learning, educational orientation, learning context, perceptions of learning.
The predominance of unicast connectivity in the current Internet infrastructure sabotages the widespread deployment of video applications. As such overlay multicast networking has been proposed to accelerate the ubiquity of video streaming in the Internet. Based on an existing overlay multicast network architecture, this paper proposes a method which aims at improving the efficiency of the streaming scheme that is part of this architecture. Instead of sending multiple streams of the same data across the network, only the essential video signals are sent in redundancy. Evaluation of the method generates promising results in preventing loss of the essential video data in burst losses of packets.
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