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A general version of the Morse-Sard theorem
JIANG Hai-yi
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(7): 754-758.
https://doi.org/10.1631/jzus.2004.0754
Let k, m, n be positive integers, and k≤2, α∈(0,1], 0k,α(Rm, Rn), A=Cr(f)={x∈Rm|rank(Df(x))≤r}, then f(A) is d-null. Thus the statement posed by Arthur Sard in 1965 can be completely solved when k≥2.
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A flower image retrieval method based on ROI feature
HONG An-xiang, CHEN Gang, LI Jun-li, CHI Zhe-ru, ZHANG Dan
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(7): 764-772.
https://doi.org/10.1631/jzus.2004.0764
Flower image retrieval is a very important step for computer-aided plant species recognition. In this paper, we propose an efficient segmentation method based on color clustering and domain knowledge to extract flower regions from flower images. For flower retrieval, we use the color histogram of a flower region to characterize the color features of flower and two shape-based features sets, Centroid-Contour Distance (CCD) and Angle Code Histogram (ACH), to characterize the shape features of a flower contour. Experimental results showed that our flower region extraction method based on color clustering and domain knowledge can produce accurate flower regions. Flower retrieval results on a database of 885 flower images collected from 14 plant species showed that our Region-of-Interest (ROI) based retrieval approach using both color and shape features can perform better than a method based on the global color histogram proposed by Swain and Ballard (1991) and a method based on domain knowledge-driven segmentation and color names proposed by Das et al.(1999).
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Decryption of pure-position permutation algorithms
ZHAO Xiao-yu, CHEN Gang, ZHANG Dan, WANG Xiao-hong, DONG Guang-chang
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(7): 803-809.
https://doi.org/10.1631/jzus.2004.0803
Pure position permutation image encryption algorithms, commonly used as image encryption investigated in this work are unfortunately frail under known-text attack. In view of the weakness of pure position permutation algorithm, we put forward an effective decryption algorithm for all pure-position permutation algorithms. First, a summary of the pure position permutation image encryption algorithms is given by introducing the concept of ergodic matrices. Then, by using probability theory and algebraic principles, the decryption probability of pure-position permutation algorithms is verified theoretically; and then, by defining the operation system of fuzzy ergodic matrices, we improve a specific decryption algorithm. Finally, some simulation results are shown.
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A minimal axiom group for rough set based on quasi-ordering
DAI Jian-hua, CHEN Wei-dong, PAN Yun-he
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(7): 810-815.
https://doi.org/10.1631/jzus.2004.0810
Rough set axiomatization is one aspect of rough set study to characterize rough set theory using dependable and minimal axiom groups. Thus, rough set theory can be studied by logic and axiom system methods. The classic rough set theory is based on equivalent relation, but rough set theory based on reflexive and transitive relation (called quasi-ordering) has wide applications in the real world. To characterize topological rough set theory, an axiom group named RT, consisting of 4 axioms, is proposed. It is proved that the axiom group reliability in characterizing rough set theory based on similar relation is reasonable. Simultaneously, the minimization of the axiom group, which requires that each axiom is an equation and each is independent, is proved. The axiom group is helpful for researching rough set theory by logic and axiom system methods.
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An integrated DBP for streams with (m,k)-firm real-time guarantee
WANG Zhi, CHEN Ji-ming, SUN You-xian
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(7): 816-826.
https://doi.org/10.1631/jzus.2004.0816
(m, k)-firm real-time or weakly hard real-time (WHRT) guarantee is becoming attractive as it closes the gap between hard and soft (or probabilistic) real-time guarantee, and enables finer granularity of real-time QoS through adjusting m and k. For multiple streams with (m, k)-firm constraint sharing a single server, an on-line priority assignment policy based on the most recent k-length history of each stream called distance based priority (DBP) has been proposed to assign priority. In case of priority equality among these head-of-queue instances, Earliest Deadline First (EDF) is used. Under the context of WHRT schedule theory, DBP is the most popular, gets much attention and has many applications due to its straightforward priority assignment policy and easy implementation. However, DBP combined with EDF cannot always provide good performance, mainly because the initial DBP does not underline the rich information on deadline met/missed distribution, specially streams in various failure states which will travel different distances to restore success states. Considering how to effectively restore the success state of each individual stream from a failure state, an integrated DBP utilizing deadline met/missed distribution is proposed in this paper. Simulation results validated the performance improvement of this proposal.
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Adaptive swarm-based routing in communication networks
LÜ Yong, ZHAO Guang-zhou, SU Fan-jun, LI Xiao-run
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2004, 5(7): 867-872.
https://doi.org/10.1631/jzus.2004.0867
Swarm intelligence inspired by the social behavior of ants boasts a number of attractive features, including adaptation, robustness and distributed, decentralized nature, which are well suited for routing in modern communication networks. This paper describes an adaptive swarm-based routing algorithm that increases convergence speed, reduces routing instabilities and oscillations by using a novel variation of reinforcement learning and a technique called momentum. Experiment on the dynamic network showed that adaptive swarm-based routing learns the optimum routing in terms of convergence speed and average packet latency.
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20 articles
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