1,135 research outputs found
Measurable Concurrence of Mixed States
We show that bipartite concurrence for rank-2 mixed states of qubits is
written by an observable which can be exactly and directly measurable in
experiment by local projective measurements, provided that four copies of the
composite quantum system are available. In addition, for a tripartite quantum
pure state of qubits, the 3-tangle is also shown to be measurable only by
projective measurements on the reduced density matrices of a pair of qubits
conditioned on four copies of the state.Comment: 3 page
Massive data delivery in unstructured peer-to-peer networks with network coding
With more and more multimedia applications on the Internet, such as IPTV, bandwidth becomes a vital bottleneck for the booming of large scale Internet based multimedia applications. Network coding is recently proposed to take advantage to use network bandwidth efficiently. In this paper, we focus on massive multimedia data, e.g. IPTV programs, transportation in peer-to-peer networks with network coding. By through study of networking coding, we pointed out that the prerequisites of bandwidth saving of network coding are: 1) one information source with a number of concurrent receivers, or 2) information pieces cached at intermediate nodes. We further proof that network coding can not gain bandwidth saving at immediate connections to a receiver end; As a result, we propose a novel model for IPTV data transportation in unstructured peer-to-peer networks with network coding. Our preliminary simulations show that the proposed architecture works very well.<br /
Performance optimization for energy-aware adaptive checkpointing in embedded real-time systems
Using additional store-checkpoinsts (SCPs) and compare-checkpoints (CCPs), we present an adaptive checkpointing for double modular redundancy (DMR) in this paper. The proposed approach can dynamically adjust the checkpoint intervals. We also design methods to calculate the optimal numbers of checkpoints, which can minimize the average execution time of tasks. Further, the adaptive checkpointing is combined with the DVS (dynamic voltage scaling) scheme to achieve energy reduction. Simulation results show that, compared with the previous methods, the proposed approach significantly increases the likelihood of timely task completion and reduces energy consumption in the presence of faults.<br /
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