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941.
WU Jian 《数字社区&智能家居》2008,(27)
介绍了一种基于最小二乘支持向量机的方法来实现土壤含水量的检测,实验结果证明该方法有效、可行,并具有一定的实用价值。 相似文献
942.
YUAN Liang-feng 《数字社区&智能家居》2008,(24)
随着计算机科学技术的迅猛发展,掌握必要的计算机基础知识和用计算机处理信息技术的能力已成为当代大学生知识、能力结构中不可或缺地重要组成部分,特别是用人单位衡量高职院校毕业生综合素质的重要条件。本文针对当前高职院校非计算机专业计算机基础教学存在的问题,从地位和作用到教学方法实习操作及师资队伍建设等方面,较全面地提出了改革举措,为高职院校计算机基础教育的改革和教学研究提供了方向。 相似文献
943.
Efficient video encryption scheme based on advanced video coding 总被引:1,自引:0,他引:1
Shiguo Lian Jinsheng Sun Guangjie Liu Zhiquan Wang 《Multimedia Tools and Applications》2008,38(1):75-89
A video encryption scheme combining with advanced video coding (AVC) is presented and analyzed in this paper, which is different
from the ones used in MPEG1/2 video encryption. In the proposed scheme, the intra-prediction mode and motion vector difference
are encrypted with the length-kept encryption algorithm (LKE) in order to keep the format compliance, and the residue data
of the macroblocks are encrypted with the residue data encryption algorithm (RDE) in order to keep low cost. Additionally,
a key distribution scheme is proposed to keep the robustness to transmission errors, which assigns sub-keys to different frames
or slices independently. The encryption scheme’s security, time efficiency and error robustness are analyzed in detail. Experimental
results show that the encryption scheme keeps file format unchanged, is secure against replacement attacks, is efficient in
computing, and is robust to some transmission errors. These properties make it a suitable choice for real-time applications,
such as secure IPTV, secure videoconference or mobile/wireless multimedia, etc.
相似文献
Shiguo LianEmail: |
944.
Olaf Beyersdorff 《Theory of Computing Systems》2008,43(2):118-135
Disjoint
-pairs are a well studied complexity-theoretic concept with important applications in cryptography and propositional proof
complexity. In this paper we introduce a natural generalization of the notion of disjoint
-pairs to disjoint k-tuples of
-sets for k≥2. We define subclasses of the class of all disjoint k-tuples of
-sets. These subclasses are associated with a propositional proof system and possess complete tuples which are defined from
the proof system.
In our main result we show that complete disjoint
-pairs exist if and only if complete disjoint k-tuples of
-sets exist for all k≥2. Further, this is equivalent to the existence of a propositional proof system in which the disjointness of all k-tuples is shortly provable. We also show that a strengthening of this conditions characterizes the existence of optimal proof
systems.
An extended abstract of this paper appeared in the proceedings of the conference CSR 2006 (Lecture Notes in Computer Science
3967, 80–91, 2006).
Supported by DFG grant KO 1053/5-1. 相似文献
945.
Prefetching in Content Distribution Networks via Web Communities Identification and Outsourcing 总被引:1,自引:0,他引:1
Antonis Sidiropoulos George Pallis Dimitrios Katsaros Konstantinos Stamos Athena Vakali Yannis Manolopoulos 《World Wide Web》2008,11(1):39-70
Content distribution networks (CDNs) improve scalability and reliability, by replicating content to the “edge” of the Internet.
Apart from the pure networking issues of the CDNs relevant to the establishment of the infrastructure, some very crucial data
management issues must be resolved to exploit the full potential of CDNs to reduce the “last mile” latencies. A very important
issue is the selection of the content to be prefetched to the CDN servers. All the approaches developed so far, assume the
existence of adequate content popularity statistics to drive the prefetch decisions. Such information though, is not always
available, or it is extremely volatile, turning such methods problematic. To address this issue, we develop self-adaptive
techniques to select the outsourced content in a CDN infrastructure, which requires no apriori knowledge of request statistics.
We identify clusters of “correlated” Web pages in a site, called Web site communities, and make these communities the basic outsourcing unit. Through a detailed simulation environment, using both real and synthetic
data, we show that the proposed techniques are very robust and effective in reducing the user-perceived latency, performing
very close to an unfeasible, off-line policy, which has full knowledge of the content popularity. 相似文献
946.
The convergence analysis of multigrid methods for boundary element equations arising from negative-order pseudo-differential operators is quite different from the usual finite element multigrid analysis for elliptic partial differential equations. In this paper, we study the convergence of geometrical multigrid methods for solving large-scale, data-sparse boundary element equations. In particular, we investigate multigrid methods for \(\mathcal{H}\)-matrices arising from the adaptive cross approximation to the single layer potential operator. 相似文献
947.
In this paper we report new results of our continuous effort on analyzing the impact of incentive mechanisms on user behavior
in BitTorrent. In this second measurement and analysis study we find that free riders’ population has significantly increased
comparing to our previous measurement study. We relate this increase to the advance in end-users’ connection speeds and to
users’ increased knowledge in BitTorrent. We also categorize free riders based on the behavior they exhibit in multiple-torrent
system into three types: cheaters, strategic and lucky peers. Furthermore, refuting the findings of other studies, we show
that peers who exploit the system in BitTorrent are both high bandwidth capacity peers and low bandwidth capacity peers. Moreover,
we argue that the Tit-for-Tat mechanism does not discriminate peers based on their bandwidth capacities and that it reacts
successfully against inter-class bandwidth capacity strategic peers. Finally, we propose a memory-backoff approach to the
optimistic unchoke policy that reduces the volume of free riding in BitTorrent.
Manaf Zghaibeh is a PhD candidate at Stevens Institute of Technology, focusing on P2P economics. He holds a Master’s Degree in Telecommunications Management from Stevens and a Bachelor’s Degree in Electrical Engineering from Damascus University. He has been a teaching assistant at NYU since 2002. Fotios Harmantzis is an Assistant Professor at the School of Technology Management at Stevens Institute of Technology. He holds a B.Sc. and M.Sc. in Computer Science from the University of Crete, a MSE in Systems Engineering from the University of Pennsylvania, a Finance MBA from Toronto/NYU, and a PhD in Electrical and Computer Engineering from the University of Toronto. Dr. Harmantzis’ research and teaching interests include mathematics of finance and risk, valuations of investments under uncertainty and economics of IT and telecom. His research work has been presented in several scientific conferences and journals. He has professional experience in the US, Canada and Europe, in the financial services, asset management and consulting business. 相似文献
Fotios C. Harmantzis (Corresponding author)Email: |
Manaf Zghaibeh is a PhD candidate at Stevens Institute of Technology, focusing on P2P economics. He holds a Master’s Degree in Telecommunications Management from Stevens and a Bachelor’s Degree in Electrical Engineering from Damascus University. He has been a teaching assistant at NYU since 2002. Fotios Harmantzis is an Assistant Professor at the School of Technology Management at Stevens Institute of Technology. He holds a B.Sc. and M.Sc. in Computer Science from the University of Crete, a MSE in Systems Engineering from the University of Pennsylvania, a Finance MBA from Toronto/NYU, and a PhD in Electrical and Computer Engineering from the University of Toronto. Dr. Harmantzis’ research and teaching interests include mathematics of finance and risk, valuations of investments under uncertainty and economics of IT and telecom. His research work has been presented in several scientific conferences and journals. He has professional experience in the US, Canada and Europe, in the financial services, asset management and consulting business. 相似文献
948.
空间滤波器阵列结构优化设计 总被引:2,自引:0,他引:2
给出了新型大型激光装置阵列化空间滤波器结构优化设计。对大口径阵列化光束超长程传输、光路控制、光束质量控制,以及支撑稳定性、震动隔离、离轴调节等关键技术进行了分析研究,对物理方案和参数进行分解。运用Pro/E软件建立阵列化空间滤波器三维实体模型,给出了阵列化空间滤波器的总体结构解决方案。对关键部件和技术指标进行了详细分析,采取了新颖的结构和相应的技术措施;运用ANSYS分析软件对结构刚性、强度、振型等指标进行分析,通过有限元仿真与CAD环境的双向嵌入优化结构;为给装置结构的适应性找到可靠的评估依据,对影响稳定性较大的器件和单元进行了微振动测试和分析。理论分析和测试结果表明,该方案达到了优化设计,是可行的。 相似文献
949.
Saliency, Scale and Image Description 总被引:6,自引:0,他引:6
950.