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Ontology-based content organization and retrieval for SCORM-compliant teaching materials in data grids

Future Generation computer Systems 2009年第6期25卷 687-694页

作者： Shih, Wen-Chung Yang, Chao-Tung Tseng, Shian-Shyong Department of Information Science and Applications Asia University Taichung 41354 Taiwan High-Performance Computing Laboratory Department of Computer Science Tunghai University Taichung 40704 Taiwan Department of Computer Science National Chiao Tung University Hsinchu 300 Taiwan

With the rapid growth of e-Learning, a tremendous amount of learning content has been developed by numerous providers. Recently, the Sharable Content Object Reference Model (SCORM) has been widely accepted as a standard of e-Learning for users to share and reuse various teaching materials. Data grids, characterized by their goal to manage large-scale dataset, are promising platforms to support sharing of geographically dispersed learning content. However, current data grid standards have not provided complete solutions to content-based information retrieval. To increase the precision of content retrieval on data grids, our idea is to propose an ontology-based approach to organize and retrieve learning content in geographically dispersed repositories. We designed a layered architecture to enable learning content organization and retrieval on data grids, implemented in a metropolitan-scale grid environment. Experimental results show that the proposed approach can precisely retrieve SCORM-compliant learning content. © 2009 Elsevier B.V. All rights reserved.

关键词： Information retrieval

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Dasher: A peer-to-peer content distribution system based on combined network coding

Dasher: A peer-to-peer content distribution system based on ...

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2009 2nd IEEE International Conference on Broadband Network and Multimedia Technology, IEEE IC-BNMT2009

作者： Kaiqian, Ou Yinlong, Xu Guanjun, Ma Yulin, Zhu Department of Computer Science and Technology University of Science and Technology of China Key Laboratory on High Performance Computing Anhui Province China

ISBN: (纸本)9781424450053

Network coding can ease the block scheduling and thus makes the distribution more efficient. However, the complexities of encoding and decoding increase sharply as the content size scales up. In this paper, we propose a coding scheme which combines chunked coding and sparse linear network coding to reduce both encoding and decoding costs of content distribution. Based on the combined scheme, we implement a P2P content distribution system, named Dasher, where Local-Rarest-First scheme is adopted for chunk scheduling. Under the same system architecture, we implement three comparative systems, a BitTorrent-like system, named Mybt, a system only with sparse coding, named Sparser and a system using chunked coding, named Chunker. We conduct extensive experiments to compare the performance among these four systems. The experimental results show that Dasher with certain chunk sizes can reduce the average downloading time up to 15% compared with Mybt, and up to 43% with Chunker. With proper chunk sizes, the downloading time of Dasher is almost the same with Sparser. The average decoding rate of Dasher is the same with Chunker, and is nearly m times as fast as Sparser, where m is the number of chunks. Moreover, with respect to robustness, Dasher performs almost as well as Chunker, better than Mybt, but worse than Sparser. ©2009 IEEE.

关键词： Network coding

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How can network coding help P2P content distribution?

How can network coding help P2P content distribution?

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2009 IEEE International Conference on Communications, ICC 2009

作者： Ma, Guanjun Xu, Yinlong Kaiqian, Ou Wen, Luo Department of Computer Science and Technology University of Science and Technology of China Key Laboratory on High Performance Computing Anhui Province China

ISBN: (纸本)9781424434350

It is well known that network coding can enhance the performance of Peer-to-Peer (P2P) content distribution systems since it benefits block scheduling. In this paper, we introduce our P2P content distribution system "SmartCode" with sparse network coding on PlanetLab. SmartCode uses pre-checking to avoid linearly dependent blocks being transmitted. Under the same system architecture, we also implement two systems "Ecode" and "LRF". Ecode is also based on sparse network coding, but without pre-checking. LRF is BitTorrent-like, using local-rarest-first for block scheduling. We conduct extensive experiments to compare the performances among the three systems. Experimental results show that the distributing time of SmartCode is reduced by 11% on average and up to 19% compared with LRF, and by 7% on average and up to 16% compared with Ecode. We also conduct experiments to analyze robustness among the three systems under the assumption that peers join in and leave a content distribution session dynamically and the seed leave the session after it has transmitted a fixed percentage of blocks over the total blocks of the content. In dynamical cases, SmartCode outperforms evidently than Ecode and LRF in downloading time and the times of peers completing the downloading. ©2009 IEEE.

关键词： Network coding

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Lexicographically fair bandwidth allocation in multi-session layered media multicast using network coding

Lexicographically fair bandwidth allocation in multi-session...

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2009 2nd IEEE International Conference on Broadband Network and Multimedia Technology, IEEE IC-BNMT2009

作者： Xiaobin, Lin Yinlong, Xu Yulin, Zhu Kaiqian, Ou Department of Computer Science and Technology University of Science and Technology of China Key Laboratory on High Performance Computing Anhui Province China

ISBN: (纸本)9781424450053

Layering techniques effectively cope with network heterogeneity encountered in media distribution. Recent work on network coding shows that the multicast throughput can be greatly improved by allowing coding operation at the intermediate nodes in the network. In this paper, we study the problem of lexicographically fair bandwidth allocation to make the receivers of different sessions share network bandwidth fairly in multi-session layered media multicast using network coding and formulate it into an integer linear programming (ILP). Because the ILP is not time efficient when the network is large, a LP-based polynomial time algorithm ApprOpt is proposed to approximate the optimal solution of the ILP. Numerical results show that the throughput of all media multicast sessions is significantly improved by network coding, and that algorithm ApprOpt allocates network bandwidth very close to the optimal solution of the ILP and utilizes network bandwidth efficiently. ©2009 IEEE.

关键词： Network coding

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Privacy vulnerabilities with background information in data perturbation

Privacy vulnerabilities with background information in data ...

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9th SIAM International Conference on Data Mining 2009, SDM 2009

作者： Liu, Lian Wang, Jie Zhang, Jun Laboratory for High Performance Scientific Computing and Computer Simulation Department of Computer Science University of Kentucky Lexington KY 40506-0046 United States

ISBN: (纸本)9781615671090

The issue of data privacy is considered a significant hindrance to the development and industrial applications of database publishing and data mining techniques. Among many privacy-preserving methodologies, data perturbation is a popular technique for achieving a balance between data utility and information privacy. It is known that the attacker's background information about the original data can play a significant role in breaching data privacy. In this paper, we analyze data perturbation's potential privacy vulnerability in the presence of known background information in privacy-preserving database publishing and data mining based on the eigenspace of the perturbed data under some constraints. We study the situation in which data privacy may be compromised with the leakage of a few original data records. We first show that additive perturbation preserves the angle between data records during the perturbation. Based on this angle-preservation property, we show that, in a general perturbation model, even the leakage of only one single original data probably degrades the privacy of perturbed data in some cases. We theoretically and experimentally show that a general data perturbation model is vulnerable from this type of background privacy breach.

关键词： Data mining

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Efficient group signature with forward secure revocation

Efficient group signature with forward secure revocation

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作者： Jin, Haimin Wong, Duncan S. Xu, Yinlong School of Computer Science University of Science and Technology of China Hefei China Key Laboratory on High Performance Computing Hefei Anhui Province China Department of Computer Science City University of Hong Kong Hong Kong

ISBN: (纸本)9783642108464

Forward secure revocation for group signature allows a revoked group member to preserve the anonymity of its signatures generated before the revocation. Most of the existing schemes of this type either have the signing or verifying complexity linear to the group size or the number of revoked members, or require the updates of signing key or public key once revocation occurs. Recently, an outstanding improvement has been made in Nakanishi et al.'s proposal [15]. However, the size of public key in their scheme is linear to the group size. In this paper, we propose a new forward secure revocable group signature scheme satisfying 1) constant signing and verifying complexity, 2) constant size in signature, public key and signing key, 3) no updates of public key or signing key are required when member joining or delete occurs. © 2009 Springer-Verlag Berlin Heidelberg.

关键词： Authentication

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Corrigendum to “A general methodology for direction-based irregular routing algorithms” [J. Parallel Distrib. Comput. 70 (2010) 363–370]

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Journal of Parallel and Distributed computing 2010年第5期70卷 623-623页

作者： R. Moraveji H. Sarbazi-Azad A.Y. Zomaya Centre for Distributed and High Performance Computing School of Information Technologies The University of Sydney NSW 2006 Australia School of Computer Science Institute for Research in Fundamental Sciences (IPM) Tehran Iran Department of Computer Engineering Sharif University of Technology Tehran Iran

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Data mining analysis to validate performance tuning practices for HPL

Data mining analysis to validate performance tuning practice...

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2009 IEEE International Conference on Cluster computing and Workshops, CLUSTER '09

作者： Tan, Tuan Zea Mong Goh, Rick Siow March, Verdi See, Simon Advanced Computing Institute of High Performance Computing Singapore Singapore Asia-Pacific Science and Technology Center Sun Microsystems Inc. Department of Computer Science National University of Singapore Singapore Department of Mechanical and Aerospace Engineering Nanyang Technological University Singapore Singapore

ISBN: (纸本)9781424450121

Applications performance is a criterion for system evaluation, and hence performance tuning for these applications is of great interest. One such benchmark application is high performance Linpack (HPL). Although guidelines exist for HPL tuning, validating these guidelines on various systems is a challenging task as a large number of configurations need to be tested. In this work, we use data mining analysis to reduce the number of configurations to be tested in validating the HPL tuning guidelines on the Ranger System. We validate that NB, P and Q are the three most important parameters to tune HPL, and that PMAP does not have a significant impact on HPL performance. We also validate the practice of tuning HPL at small N using data mining analysis. We find that the value of N selected for tuning should not be significantly smaller than the largest N that can fit into the system memory. Our results indicate that data mining could be further applied to application performance tuning. © 2009 IEEE.

关键词： Data mining

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Privacy preservation in social networks with sensitive edge weights

Privacy preservation in social networks with sensitive edge ...

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9th SIAM International Conference on Data Mining 2009, SDM 2009

作者： Liu, Lian Wang, Jie Liu, Jinze Zhang, Jun Laboratory for High Performance Scientific Computing and Computer Simulation Department of Computer Science University of Kentucky Lexington KY 40506-0046 United States Computer Science Department Minnesota State University Mankato 273 Wissink Hall Mankato MN 56001 United States Department of Computer Science College of Engineering University of Kentucky 237 Hardymon Lexington KY 40506-0046 United States

ISBN: (纸本)9781615671090

With the development of emerging social networks, such as Facebook and MySpace, security and privacy threats arising from social network analysis bring a risk of disclosure of confidential knowledge when the social network data is shared or made public. In addition to the current social network anonymity de-identification techniques, we study a situation, such as in a business transaction network, in which weights are attached to network edges that are considered to be confidential (e.g., transactions). We consider perturbing the weights of some edges to preserve data privacy when the network is published, while retaining the shortest path and the approximate cost of the path between some pairs of nodes in the original network. We develop two privacy-preserving strategies for this application. The first strategy is based on a Gaussian randomization multiplication, the second one is a greedy perturbation algorithm based on graph theory. In particular, the second strategy not only yields an approximate length of the shortest path while maintaining the shortest path between selected pairs of nodes, but also maximizes privacy preservation of the original weights. We present experimental results to support our mathematical analysis.

关键词： Graph theory

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A performance-based Dynamic Loop Partitioning on Grid computing Environments

A Performance-based Dynamic Loop Partitioning on Grid Comput...

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IEEE International Conference on high performance computing and Communications (HPCC)

作者： Chao-Tung Yang Lung-Hsing Cheng High-Performance Computing Laboratory Department of Computer Science Tunghai University Taichung Taiwan

Loop scheduling on parallel and distributed systems has been a critical problem. Furthermore, it becomes more difficult to deal with on the emerging heterogeneous grid environments. In the past, some loop self-scheduling schemes have been proposed to be applicable to heterogeneous gird environments. In this paper, we propose a performance-based approach, which partitions loop iterations according to the performance weight of nodes. To verify the proposed approach, a grid testbed that consists four schools is built, and matrix multiplication example is implemented to be executed in this testbed. Experimental results show that the proposed approach performs better than previous schemes.

关键词： Grid computing Processor scheduling Dynamic scheduling Central Processing Unit Distributed computing Testing Clocks high performance computing Concurrent computing performance analysis

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