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Non-interactive identity-based threshold signature scheme without random oracles
Xun SUN, Jian-hua LI, Shu-tang YANG, Gong-liang CHEN
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 727-736.
https://doi.org/10.1631/jzus.A0720028
A (t, n) threshold signature scheme distributes the secret key and hence the signing ability to n players in a way that any set of t+1 or more honest players can collaborate to sign, while any set of t players cannot. In this paper we propose an identity-based threshold signature (IBTHS) scheme from bilinear pairings. The signing phase of our scheme is non-interactive, meaning that the signing players do not need to talk to each other. We prove our scheme secure (i.e., unforgeable and robust) in the standard model (i.e., without random oracles). No earlier proposed IBTHS scheme achieved even one of the features of being non-interactive (in the signing phase) and secure in the standard model.
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Integrated criteria for covert channel auditing
Chang-da WANG, Shi-guang JU
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 737-743.
https://doi.org/10.1631/jzus.A071510
A new concept, the security level difference of a covert channel, is presented, which means the security level span from the sender to the receiver of the covert channel. Based on this, the integrated criteria for covert channel auditing are given. Whereas TCSEC (Trusted Computer System Evaluation Criteria) or CC (Common Criteria for Information Technology Security Evaluation) only use the bandwidth to evaluate the threat of covert channels, our new criteria integrate the security level difference, the bandwidth sensitive parameter, bandwidth, duration and instantaneous time of covert channels, so as to give a comprehensive evaluation of the threat of covert channels in a multilevel security system.
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Bottom-up mining of XML query patterns to improve XML querying
Yi-jun BEI, Gang CHEN, Jin-xiang DONG, Ke CHEN
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 744-757.
https://doi.org/10.1631/jzus.A071551
Querying XML data is a computationally expensive process due to the complex nature of both the XML data and the XML queries. In this paper we propose an approach to expedite XML query processing by caching the results of frequent queries. We discover frequent query patterns from user-issued queries using an efficient bottom-up mining approach called VBUXMiner. VBUXMiner consists of two main steps. First, all queries are merged into a summary structure named “compressed global tree guide” (CGTG). Second, a bottom-up traversal scheme based on the CGTG is employed to generate frequent query patterns. We use the frequent query patterns in a cache mechanism to improve the XML query performance. Experimental results show that our proposed mining approach outperforms the previous mining algorithms for XML queries, such as XQPMinerTID and FastXMiner, and that by caching the results of frequent query patterns, XML query performance can be dramatically improved.
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Adaptive XML to relational mapping: an integrated approach
Tian-lei HU, Gang CHEN
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 758-769.
https://doi.org/10.1631/jzus.A0720103
Storing and querying XML (eXtensible Markup Language) data in relational form can exploit various services offered by modern relational database management systems (RDBMSs). Due to structural complexity of XML, there are many equivalent relational mapping schemes for the same XML data and queries. In this paper, we propose the adaptive XML to relational mapping (AX2RM) system, which considers finding optimal XML to relational (X2R) mapping as four separate but correlated procedures: logical database design, data scale estimation, workload transformation, and physical database design. We view the whole process as an autonomic computing problem and formalize the adaptive X2R mapping problem. Search spaces for each procedure are investigated individually, and five approaches for finding the optimal mapping are studied. We propose an integrated approach with greedy pruning (IT-GP), which views the mapping procedures as a whole and exploits heuristic rules in each procedure to prune impossible mappings as early as possible. Evaluation of these approaches shows the validity and high efficiency of IT-GP.
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Schedulability analysis for linear transactions under fixed priority hybrid scheduling
Zhi-gang GAO, Zhao-hui WU
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 776-785.
https://doi.org/10.1631/jzus.A071411
In hard real-time systems, schedulability analysis is not only one of the important means of guaranteeing the timelines of embedded software but also one of the fundamental theories of applying other new techniques, such as energy savings and fault tolerance. However, most of the existing schedulability analysis methods assume that schedulers use preemptive scheduling or non-preemptive scheduling. In this paper, we present a schedulability analysis method, i.e., the worst-case hybrid scheduling (WCHS) algorithm, which considers the influence of release jitters of transactions and extends schedulability analysis theory to timing analysis of linear transactions under fixed priority hybrid scheduling. To the best of our knowledge, this method is the first one on timing analysis of linear transactions under hybrid scheduling. An example is employed to demonstrate the use of this method. Experiments show that this method has lower computational complexity while keeping correctness, and that hybrid scheduling has little influence on the average worst-case response time (WCRT), but a negative impact on the schedulability of systems.
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Two-stage evolutionary algorithm for dynamic multicast routing in mesh network
Li ZHU, Zhi-shu LI, Liang-yin CHEN, Yan-hong CHENG
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 791-798.
https://doi.org/10.1631/jzus.A071519
In order to share multimedia transmissions in mesh networks and optimize the utilization of network resources, this paper presents a Two-stage Evolutionary Algorithm (TEA), i.e., unicast routing evolution and multicast path composition, for dynamic multicast routing. The TEA uses a novel link-duplicate-degree encoding, which can encode a multicast path in the link-duplicate-degree and decode the path as a link vector easily. A dynamic algorithm for adding nodes to or removing nodes from a multicast group and a repairing algorithm are also covered in this paper. As the TEA is based on global evaluation, the quality of the multicast path remains stabilized without degradation when multicast members change over time. Therefore, it is not necessary to rearrange the multicast path during the life cycle of the multicast sessions. Simulation results show that the TEA is efficient and convergent.
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Similarity-based denoising of point-sampled surfaces
Ren-fang WANG, Wen-zhi CHEN, San-yuan ZHANG, Yin ZHANG, Xiu-zi YE
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 807-815.
https://doi.org/10.1631/jzus.A071465
A non-local denoising (NLD) algorithm for point-sampled surfaces (PSSs) is presented based on similarities, including geometry intensity and features of sample points. By using the trilateral filtering operator, the differential signal of each sample point is determined and called “geometry intensity”. Based on covariance analysis, a regular grid of geometry intensity of a sample point is constructed, and the geometry-intensity similarity of two points is measured according to their grids. Based on mean shift clustering, the PSSs are clustered in terms of the local geometry-features similarity. The smoothed geometry intensity, i.e., offset distance, of the sample point is estimated according to the two similarities. Using the resulting intensity, the noise component from PSSs is finally removed by adjusting the position of each sample point along its own normal direction. Experimental results demonstrate that the algorithm is robust and can produce a more accurate denoising result while having better feature preservation.
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In-package P/G planes analysis and optimization based on transmission matrix method
Yin-jun WANG, Cheng ZHUO, Jun-yong DENG, Jin-fang ZHOU, Kang-sheng CHEN
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 849-857.
https://doi.org/10.1631/jzus.A071489
Power integrity (PI) has become a limiting factor for the chip’s overall performance, and how to place in-package decoupling capacitors to improve a chip’s PI performance has become a hot issue. In this paper, we propose an improved transmission matrix method (TMM) for fast decoupling capacitance allocation. An irregular grid partition mechanism is proposed, which helps speed up the impedance computation and complies better with the irregular power/ground (P/G) plane or planes with many vias and decoupling capacitors. Furthermore, we also ameliorate the computation procedure of the impedance matrix whenever decoupling capacitors are inserted or removed at specific ports. With the fast computation of impedance change, in-package decoupling capacitor allocation is done with an efficient change based method in the frequency domain. Experimental results show that our approach can gain about 5× speedup compared with a general TMM, and is efficient in restraining the noise on the P/G plane.
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An integrated classification method for thematic mapper imagery of plain and highland terrains
Shan-long LU, Xiao-hua SHEN, Le-jun ZOU, Chang-jiang LI, Yan-jun MAO, Gui-fang ZHANG, Wen-yuan WU, Ying LIU, Zhong ZHANG
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2008, 9(6): 858-866.
https://doi.org/10.1631/jzus.A071469
The classification of thematic mapper imagery in areas with strong topographic variations has proven problematic in the past using a single classifier, due to the changing sun illumination geometry. This often results in the phenomena of identical object with dissimilar spectrum and different objects with similar spectrum. In this paper, an integrated classification method that combines a decision tree with slope data, tasseled cap transformation indices and maximum likelihood classifier is introduced, to find an optimal classification method for thematic mapper imagery of plain and highland terrains. A Landsat 7 ETM+ image acquired over Hangzhou Bay, in eastern China was used to test the method. The results indicate that the performance of the integrated classifier is acceptably good in comparison with that of the existing most widely used maximum likelihood classifier. The integrated classifier depends on hypsography (variation in topography) and the characteristics of ground truth objects (plant and soil). It can greatly reduce the influence of the homogeneous spectrum caused by topographic variation. This integrated classifier might potentially be one of the most accurate classifiers and valuable tool for land cover and land use mapping of plain and highland terrains.
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16 articles
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