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In this work, we have put forth two different protocols to address a concrete secure multi-party computational (MPC) problem related to a triangle, of which the coordinates of the three vertices are confidentially kept by the three participants, respectively. The three parties wish to collaboratively compute the area of this triangle while preserving their own coordinate privacy. As one of the merits, our protocols employ weaker assumptions of the existence of pseudorandom generators. In particular, unlike massive secure MPC protocols that rely a lot on oblivious transfer, ours utilize a new computing idea called “pseudorandom-then-rounding” method to avoid this burdensome obstacle. The two protocols are based on different theorems, while they both make use of the same underlying idea. At last, we provide a detailed proof for the first protocol by a series of security reductions of our newly defined games, which seems somewhat stronger than the previous simulation-based proofs and a proof sketch for the second one. Analysis and discussion about the reasons are provided as well to round off our work. 相似文献
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The MapReduce framework has become the de facto standard for big data processing due to its attractive features and abilities. One is that it automatically parallelizes a job into multiple tasks and transparently handles task execution on a large cluster of commodity machines. The increasing heterogeneity of distributed environments may result in a few straggling tasks, which prolong job completion. Speculative execution is proposed to mitigate stragglers. However, the existing speculative execution mechanism could not work efficiently as many speculative tasks are still slower than their original tasks. In this paper, we explore an approach to increase the efficiency of speculative execution, and further improve MapReduce performance. We propose the Partial Speculative Execution (PSE) strategy to make speculative tasks start from the checkpoint. By leveraging the checkpoint of original tasks, PSE can eliminate the costs of re-reading, re-copying, and re-computing the processed data. We implement PSE in Hadoop, and evaluate its performance in terms of job completion time and the efficiency of speculative execution under several kinds of classical workloads. Experimental results show that, in heterogeneous environments with stragglers, PSE completes jobs 56 % faster than that with no speculation and 12 % faster than that with LATE, an improved speculative execution algorithm. In addition, on average PSE can improve the efficiency of speculative execution by 24 % compared to LATE. 相似文献
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The widespread availability of digital learning resources in a variety of media formats offers the possibility to make a profound difference in education. This potential has not been fully realised for range of interrelated reasons. In this paper we study the key characteristics of learning resources that have proved effective in changing learning and teaching, and relate them to existing frameworks for understanding resources. We outline the relationships between resources, their users, and the way they are used, and explore issues that influence practitioners in choosing a particular resource. Our study is based on a review of resources for e-learning and chemistry in post-compulsory education, undertaken for the UK Joint Information Systems Committees (JISC), as part of a wider study examining ‘The Effectiveness of Resources, Tools and Support Services used by Tutors in Designing and Delivering E-Learning Activities’. 相似文献
67.
为降低H.264中运动估计的复杂性,通过对自然图像序列的分析,提出了一种基于块的运动特征的快速自适应搜索算法。该算法充分利用视频序列中当前块的运动状态,根据不同块的运动情况合理选择运动搜索模板。实验表明,该算法在保证重构图像质量的前提下,编码速度有了显著提高,保证了实时应用的要求。 相似文献
68.
一种空间自适应正则化MAP超分辨率重建算法 总被引:1,自引:0,他引:1
提出一种简单、通用的基于正则化技术的自适应MAP超分辨率重建算法。与以往算法不同,该方法引入了局部空间自适应正则化参数,弥补了传统算法对图像自身的局部特性缺乏考虑的不足。算法通过迭代的方式,利用中间重建结果不断对正则化参数进行更新,并最终得到重建图像。实验结果表明,该方法可以根据不同图像序列的特点以及图像的局部灰度特性,自适应地确定相应的正则化参数,并找到最优解,有效地保护了高分辨率图像的细节信息。 相似文献
69.
介绍了以DSP芯片TMS320F2812为核心设计的控制平台、利用半导体制冷器和光功率传感器调节激光二极管工作温度和发射功率的控制系统;设计了具有良好性能的模拟通道,提出了针对特定调节对象的PID算法.结合优化设计的执行单元实现了很好的控制效果,有效地提高了激光二极管系统的稳定性和可靠性;设计的控制系统在环境温度-10℃~50℃时能够达到±0.03℃的控制精度. 相似文献
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