40285763
Critical Points for Interactive Schema Matching
Experience suggests that fully automated schema matching is infeasible, especially for n-to-m matches involving semantic functions. It is therefore advisable for a matching algorithm not only to do as much as possible automatically, but also to accurately identify the critical points where user input is maximally useful. Our matching algorithm combines several existing approaches, with a new emphasis on using the context provided by the way elements are embedded in paths. A prototype tested on biological data (gene sequence, DNA, RNA, etc.) and on bibliographic data, shows significant performance improvements from user feedback and context checking. In non-interactive mode on the purchase order schemas, it compares favorably with COMA, the most mature schema matching system in literature, and also correctly identifies critical points for user input.
12571017
A Metadata Integration Assistant Generator for Heterogeneous Distributed Databases
This paper describes a metadata interchange approach for semi-automatedin tegration of heterogeneous distributedd atabases. Our system prototype uses distributed metadata to generate a GUI tool for a meta-user (who does the metadata integration) to describe mappings between master and source databases by assigning index number and specifying conversion function names; the system uses Quilt as its XML query language. The queries for the local databases being transparent for users are generated, which is based on the metadata built semi-automatically. An experiment testing feasibility is reportedin which 3 different publishers' databases are integrated.
10216231
On the Security of Two Threshold Signature Schemes with Traceable Signers
A (t,n) threshold signature scheme allows t or more group members to generate signatures on behalf of a group with n members, while any t-1 or less members cannot do the same thing. In 2001, based on a variant of ElGamal digital signature scheme, Li et al. proposed two (t,n) threshold signature schemes with traceable signers. One of their schemes needs the assistance of a mutually trusted center, while the other does not. In this paper, we present a security analysis on their schemes. We first point out that in fact signers in their schemes are untraceable, since anybody can convert a valid threshold signature into a new one such that another subset of group members will be wrongly considered as the signers of the new threshold signature for the same message. Furthermore, we demonstrate an attack to show that their second threshold signature scheme is insecure. In our attack, (n-t+1) colluding members can control the group secret key. Therefore, they can generate valid threshold signature for any message without the help of other members. Furthermore, honest members cannot detect this security flaw in the system, since any t members can generate threshold signatures according to the prescribed protocols.
17122000
Efficient and robust key management for large mobile ad hoc networks
Existing research efforts in key management can only handle very limited number of nodes and are vulnerable to active attacks. In addition, the flexibility and adaptivity of handling dynamic risks in different parts of networks, although critical in the practical usages of ad hoc networks, have been largely ignored. In this paper, we propose a novel hierarchical scheme based on threshold cryptography to address both security and efficiency issues of key management and certification service in Mobile Ad hoc Network (MANET). The main contributions of our key management scheme include: 1. providing various parts of MANET the flexibility of selecting appropriate security configurations, according to the risks faced; 2. providing the adaptivity to cope with rapidly-changing environments; 3. handling of MANETs with a large number of nodes; 4. issuing certificates with different levels of assurance. We also propose two algorithms, which can be used independently from the hierarchical structure, to protect certification services in ad hoc networks from active attacks. Our simulation results show that, compared to the previous work [16,18,19], our second algorithm is much faster in a friendly environment. When the key length is 1024 bits, the process of generating or renewing a certificate in our second algorithm is around six to eight times faster, and the process of generating partial certificates in our second algorithm is around 20-80 times faster. The latter advantage is critical in MANET where intrinsically the less help a node requests from its neighbors, the higher is the chance of obtaining the help. Furthermore, simulation results also show that our two algorithms work well in a hostile environment in which existing schemes work poorly.
8431943
GPU-friendly warped display for scope-maintained video surveillance
In this paper, we propose an efficient technique for warped display of surveillance video signal. Usually, there are regions of interest (ROIs) in video surveillance, such as entrance or exit, and moving objects or persons. The surveillant has two or more conflicting goals in mind. He/She wants to blow up the ROIs, but also wants to have an overview of the whole surveillance scope. The proposed method solves this conflict by warping the input video signal in real time fashion. First, multiple ROIs are detected. Then, the mesh for texture mapping is deformed, according to the position and shape of the ROIs. The original video frame is mapped as a texture on the deformed mesh to produce the warped effect. Mesh deformation and texture mapping are accelerated by modern graphics processing units (GPU). By allocating more display space for ROIs, the proposed technique highlights such important regions and assists the surveillant to locate them effectively. By experiments, we show that the proposed method is effective and efficient.
3417026
A rule generation algorithm based on granular computing
Granular computing has been applied in many fields to solve problems or describe problem spaces at different granularities and hierarchies. In this paper, a rule generation algorithm based on granular computing (RGAGC) is developed. RGAGC is a valid method to generate rules from the granule space. Compared with many classic decision tree algorithms, RGAGC generates a single rule granule in each step instead of selecting a suitable attribute. It is a more general algorithm for rule generation, since it could generate rules from the granule space without considering the problem of selecting an attribute according to some measure. On the other hand, in order to improve the performance of rule granule generation, the "false preserving" property of quotient space theory is used as a strategy to control the process of rule granule generation, so that RGAGC could generate rule granules from the granule space quickly. Our simulation experiment results prove that RGAGC is valid.
16185032
Using Social Contextual Information to Match Criminal Identities
Criminal identity matching is crucial to crime investigation in law enforcement agencies. Existing techniques match identities that refer to the same individuals based on simple identity features. These techniques are subject to several problems. First, there is an effectiveness trade-off between the false negative and false positive rates. The improvement of one rate usually lowers the other. Second, in some situations such as identity theft, simple-feature-based techniques are unable to match identities that have completely different identity feature values. We argue that the information about the social context of an individual may provide additional information for revealing the individual’s identity, helping improve the effectiveness of identity matching techniques. We define two types of social contextual features: role-based personal features and social group features. Experiments showed that social contextual features, especially the structural similarity and the relational similarity, significantly improved the precision without lowering the recall of criminal identity matching tasks.