Dec 2009, Volume 3 Issue 4
    

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  • Research articles
    Socially inspired search and ranking in mobile social networking: concepts and challenges
    Yufeng WANG, Akihiro NAKAO, Jianhua MA,
    2009, 3(4): 435-444. https://doi.org/10.1007/s11704-009-0059-6
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    In this paper, we provide an overview of challenges in mobile search and ranking, and envision the fundamental features that should be satisfied. We argue that two principles will help improve the relevance and quality of mobile search and ranking: the first one is to examine both intrinsic content features and context of items (usage statistics and social features, etc.); and the second one lies in that no algorithms can replace the objectivity of a human being—let users define the sites that they feel are relevant, leverage their social networks, and over time see their results become highly personalized. Specifically, wireless-virtualcommunity- based mobile search and ranking architecture is proposed in this paper, in which communities act as a first class abstraction for information sharing. Then, we introduce briefly the potential procedures of achieving high relevance and quality in mobile search and ranking based on wireless virtual community.
  • Research articles
    Detecting academic experts by topic-sensitive link analysis
    Hao WU, Yijian PEI, Jiang YU,
    2009, 3(4): 445-456. https://doi.org/10.1007/s11704-009-0038-y
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    The problem of academic expert finding is concerned with finding the experts on a named research field. It has many real-world applications and has recently attracted much attention. However, the existing methods are not versatile and suitable for the special needs from academic areas where the co-authorship and the citation relation play important roles in judging researchers’ achievements. In this paper, we propose and develop a flexible data schema and a topic-sensitive co-pagerank algorithmcombined with a topic model for solving this problem. The main idea is to measure the authors’ authorities by considering topic bias based on their social networks and citation networks, and then, recommending expert candidates for the questions. To infer the association between authors and topics, we draw a probability model from the latent Dirichlet allocation (LDA) model. We further propose several techniques such as reasoning the interested topics of the query and integrating ranking metrics to order the practices. Our experiments show that the proposed strategies are all effective to improve the retrieval accuracy.
  • Research articles
    Knowledge fusion framework based on Web page texts
    Sikang HU, Yuanda CAO,
    2009, 3(4): 457-464. https://doi.org/10.1007/s11704-009-0035-1
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    With the proliferation ofWeb page texts, it is important to fuse these texts to useful documents that users need. However, there is still no complete and unified theoretical model for studying the research issues including redundancy, localization, and fuzziness existing in the process of fusing Web page texts. This paper proposes a fusion framework calledWeb Pages Knowledge Fusion Framework (WPKFF) to synthesize the knowledge of Web page texts. First, sentences in Web page texts are extracted and transformed into triple semantic net as knowledge representation. Then a semantic description of attribute fusion rules, description information fusion rules and attribute-value and description information fusion rules are defined in WPKFF. These rules are used to fuse the attributes of same domain concepts in triple semantic net. The features of attributes include description (string) and value data (number). The results of the experiments indicate that the fusion framework is a feasible model in terms of precision and recall.
  • Research articles
    Measurement of refinement and correctness
    Hengyang WU,
    2009, 3(4): 465-471. https://doi.org/10.1007/s11704-009-0016-4
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    The purpose of this paper is to introduce a measurement approach of refinement and correctness of probabilistic programs. That is, we define the refinement degree and the correctness degree by the weakest precondition transformers. This kind of measurement indicates the degree that a program is refined by another and the degree that a program is correct with respect to a pair of precondition and postcondition. Some properties of this measurement, for example continuity, are discussed.
  • Research articles
    Geometric algorithm for point projection and inversion onto Bézier surfaces
    Jinting XU, Weijun LIU, Hongyou BIAN, Lun LI, Jianhuang WU,
    2009, 3(4): 472-476. https://doi.org/10.1007/s11704-009-0034-2
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    This paper presents an accurate and efficient method for the computation of both point projection and inversion onto Bézier surfaces. First, these two problems are formulated in terms of solution of a polynomial equation with u and v variables expressed in the Bernstein basis. Then, based on subdivision of the Bézier surface and the recursive quadtree decomposition, a novel solution method is proposed. The computation of point projection is shown to be equivalent to the geometrically intuitive intersection of a surface with the u-v plane. Finally, by comparing the distances between the test point and the candidate points, the closest point is found. Examples illustrate the feasibility of this method.
  • Research articles
    Validation indices for projective clustering
    Lifei CHEN, Shanjun HE, Qingshan JIANG,
    2009, 3(4): 477-484. https://doi.org/10.1007/s11704-009-0051-1
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    Cluster validation is a major issue in cluster analysis of data mining, which is the process of evaluating performance of clustering algorithms under varying input conditions. Many existing validity indices address clustering results of low-dimensional data. Within high-dimensional data, many of the dimensions are irrelevant, and the clusters usually only exist in some projected subspaces spanned by different combinations of dimensions. This paper presents a solution to the problem of cluster validation for projective clustering. We propose two new measurements for the intracluster compactness and intercluster separation of projected clusters. Based on these measurements and the conventional indices, three new cluster validity indices are presented. Combined with a fuzzy projective clustering algorithm, the new indices are used to determine the number of projected clusters in high-dimensional data. The suitability of our proposal has been demonstrated through an empirical study using synthetic and real-world datasets.
  • Research articles
    On the equal-weight symmetric Boolean functions
    Yu ZHOU, Guozhen XIAO,
    2009, 3(4): 485-493. https://doi.org/10.1007/s11704-009-0002-x
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    Two important classes of symmetric Boolean functions are the equal-weight Boolean functions and the elementary (or homogeneous) symmetric Boolean functions. In this paper we studied the equal-weight symmetric Boolean functions. First the Walsh spectra of the equalweight symmetric Boolean functions are given. Second the sufficient and necessary condition on correlation-immunity of the equal-weight symmetric Boolean function is derived and other cryptology properties such as the nonlinearity, balance and propagation criterion are taken into account. In particular, the nonlinearity of the equal-weight symmetric Boolean functions with n(n≥10) variables is determined by their Hamming weight. Considering these properties will be helpful in further investigations of symmetric Boolean functions.
  • Research articles
    Security evaluation against differential and linear cryptanalyses for Feistel ciphers
    Nianping WANG, Chenhui JIN,
    2009, 3(4): 494-502. https://doi.org/10.1007/s11704-009-0049-8
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    To evaluate the security against differential and linear cryptanalyses for Feistel ciphers with substitutionpermutation network (SPN) round function, we consider the lower bounds of the number of differential and linear active s-boxes, which provides the upper bounds of the maximum differential and linear characteristic probabilities of Feistel ciphers. Concretely, using differential and linear branch numbers Bd, Bl of P transformation within the round function, we give new lower bounds of the number of active s-boxes in any consecutive rounds of Feistel ciphers, respectively. Furthermore, we show that our results are better than others by comparing these results.
  • Research articles
    A bipartite model for load balancing in grid computing environments
    Wenchao JIANG, Matthias BAUMGARTEN, Yanhong ZHOU, Hai JIN,
    2009, 3(4): 503-523. https://doi.org/10.1007/s11704-009-0036-0
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    In this paper, a bipartite model for load balancing (LB) in grid computing environments, called Transverse viewpoint-based Bi-Tier model (TBT), is proposed. TBT can efficiently eliminate topology mismatching between overlay- and physical-networks during the load transfer process. As an implementation of TBT, a novel LB policy called M2ON (Min-cost and Max-flow Channel based Overlay Network) is presented. In M2ON, the communication capability is denoted as M2C (Min-cost and Max-flow Channel) which is obtained using a Labeled Tree Probing (LTP) method. The computing capacity is denoted as the Idle Factor (IF) which is obtained from the semantic overlay. The higher- and lower-level characteristics are combined into an Integrated Impacting Factor (IIF) using a Double Linear Inserting (DLI) function. Based on IIF, optimal topology matching can be achieved in the LB process. Extensive experiments and simulations have been performed and will be discussed. The results show that M2ON achieves more accurate topology matching with a minimum increment in the overall locating time yet achieving higher system performance as a whole.
  • Research articles
    Approximation algorithm for constructing data aggregation trees for wireless sensor networks
    Deying LI, Qinghua ZHU, Jiannong CAO,
    2009, 3(4): 524-534. https://doi.org/10.1007/s11704-009-0039-x
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    This paper considers the problem of constructing data aggregation trees in wireless sensor networks (WSNs) for a group of sensor nodes to send collected information to a single sink node. The data aggregation tree contains the sink node, all the source nodes, and some other non-source nodes. Our goal of constructing such a data aggregation tree is to minimize the number of non-source nodes to be included in the tree so as to save energies. We prove that the data aggregation tree problem is NP-hard and then propose an approximation algorithm with a performance ratio of four and a greedy algorithm. We also give a distributed version of the approximation algorithm. Extensive simulations are performed to study the performance of the proposed algorithms. The results show that the proposed algorithms can find a tree of a good approximation to the optimal tree and has a high degree of scalability.
  • Research articles
    Virtual node based adaptive routing in wireless ad hoc networks
    Gang LI, Hongmei SUN,
    2009, 3(4): 535-542. https://doi.org/10.1007/s11704-009-0061-z
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    It is a challenge to make the routes quickly adapt to the changed network topology when nodes fail in a wireless ad hoc network. In this paper, we propose an adaptive routing protocol, which groups the network nodes into virtual nodes according to their data transfer capabilities and creates virtual-node-based routes. The protocol can accommodate the routes to node failures by adaptively pdating the virtual nodes and just-in-time using available nodes during data transmission. The simulations indicate that the proposed protocol can keep the routes failed-node-freewhen the available virtual node members cover the failed nodes scattering area.
  • Research articles
    Research of localization approach for the new comer in wireless sensor networks
    Wei QU, Zhe LI,
    2009, 3(4): 543-549. https://doi.org/10.1007/s11704-009-0037-z
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    When some sensor nodes of wireless sensor networks (WSN) can not work forever because of long-term work or failure caused by attack, a few new comers need to be put into the network. For the application of the new comer in WSN, an accurate and effective localization algorithm based on received signal strength indicator (RSSI) is proposed. Through a few necessary nodes’ participation and the collaboration between the new comer and its one-hop and two-hop neighbor nodes, the accurate localization of the new comer is achieved. Simulation results show that the localization accuracy is about 17% of sensor node’s radio frequency (RF) transmission range, when the measurement error is 10% and the standard deviation for Gauss error of original sensor nodes’ coordinate is about 20% of sensor node’s RF transmission range. Simulation results also verify nice stability and adaptability of the new comer’s location algorithm.
  • Research articles
    A new parallel scheduling system for multiple radio wireless mesh network
    Yun HU, Shoubao YANG, Qi ZHANG, Dapeng WANG, Qinwei SHEN,
    2009, 3(4): 550-559. https://doi.org/10.1007/s11704-009-0033-3
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    To enhance the capacity of wireless mesh networks, a key technique is widely investigated which is the usage of multi-radio and multi-channel diversity. In this paper, a new parallel scheduling system is proposed which exploits MAC diversities by transmitting packets on the radios opportunistically. Compared with conventional packet transmission which follows “one flow one radio”, the new system uses radio diversity to transmit the packets on different radios simultaneously. Two kernel components of this system are selection module and schedule module. A localized selecting algorithm is implemented in the selection model to choose the right radios based on the quality of wireless links; two distributed packet-scheduling algorithms are optional with the schedule component. Finally, a routing metric adapting this system is presented. We have carried out a comprehensive performance evaluation of this system using ns-2. Simulation results show that it can successfully harness diversity of multi-radio and multi-channel to provide considerable improvements over a baseline multi-channel system in several situations.
  • Research articles
    Algorithm and axiomatization of rough fuzzy sets based finite dimensional fuzzy vectors
    Mingfen WU,
    2009, 3(4): 560-568. https://doi.org/10.1007/s11704-009-0060-0
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    Rough sets, proposed by Pawlak and rough fuzzy sets proposed by Dubois and Prade were expressed with the different computing formulas that were more complex and not conducive to computer operations. In this paper, we use the composition of a fuzzy matrix and fuzzy vectors in a given non-empty finite universal, constitute an algebraic system composed of finite dimensional fuzzy vectors and discuss some properties of the algebraic system about a basis and operations. We give an effective calculation representation of rough fuzzy sets by the inner and outer products that unify computing of rough sets and rough fuzzy sets with a formula. The basis of the algebraic system play a key role in this paper. We give some essential properties of the lower and upper approximation operators generated by reflexive, symmetric, and transitive fuzzy relations. The reflexive, symmetric, and transitive fuzzy relations are characterized by the basis of the algebraic system. A set of axioms, as the axiomatic approach, has been constructed to characterize the upper approximation of fuzzy sets on the basis of the algebraic system.